| MAA | South Dakota/Iowa | Wellmark Blue-Cross Blue-Shield |
| MAB | Florida | Florida-Blue |
| MAC | Maryland/District of Columbia/Northern Virginia | Carefirst Blue-Cross Blue-Shield |
| MAD | Alaska | Premera Blue-Cross Blue-Shield of Alaska |
| MAE | Indiana | Anthem Blue-Cross Blue-Shield of Indiana |
| MAF | Maryland/District of Columbia/Northern Virginia | Carefirst Blue-Cross Blue-Shield |
| MAG | New Mexico | Blue-Cross Blue-Shield of New Mexico |
| MAH | Virginia | Anthem Blue-Cross Blue-Shield of Virginia |
| MAI | South Dakota/Iowa | Wellmark Blue-Cross Blue-Shield |
| MAJ | - | Unallocated/Not Assigned |
| MAK | Kentucky | Anthem Blue-Cross Blue-Shield of Kentucky |
| MAL | Maryland/District of Columbia/Northern Virginia | Carefirst Blue-Cross Blue-Shield |
| MAM | Maryland/District of Columbia/Northern Virginia | Carefirst Blue-Cross Blue-Shield |
| MAN | Maine | Anthem Blue-Cross Blue-Shield of Maine |
| MAO | Florida | Florida-Blue |
| MAP | Colorado | Anthem Blue-Cross Blue-Shield of Colorado |
| MAQ | Florida | Florida-Blue |
| MAR | Georgia | Anthem Blue-Cross Blue-Shield of Georgia |
| MAS | Georgia | Anthem Blue-Cross Blue-Shield of Georgia |
| MAT | Texas | Blue-Cross Blue-Shield of Texas |
| MAU | South Dakota/Iowa | Wellmark Blue-Cross Blue-Shield |
| MAV | Ohio | Anthem Blue-Cross Blue-Shield of Ohio |
| MAW | Connecticut | Anthem Blue-Cross Blue-Shield of Connecticut |
| MAX | Illinois | Blue-Cross Blue-Shield of Illinois |
| MAY | Nebraska | Blue-Cross Blue-Shield of Nebraska |
| MAZ | South Dakota/Iowa | Wellmark Blue-Cross Blue-Shield |
| MBA | Ohio | Anthem Blue-Cross Blue-Shield of Ohio |
| MBB | Colorado | Anthem Blue-Cross Blue-Shield of Colorado |
| MBC | Tennessee | Blue-Cross Blue-Shield of Tennessee |
| MBD | Maryland/District of Columbia/Northern Virginia | Carefirst Blue-Cross Blue-Shield |
| MBE | Nebraska | Blue-Cross Blue-Shield of Nebraska |
| MBF | Georgia | Anthem Blue-Cross Blue-Shield of Georgia |
| MBG | Alabama | Blue-Cross Blue-Shield of Alabama |
| MBH | Alabama | Blue-Cross Blue-Shield of Alabama |
| MBI | Michigan | Blue-Cross Blue-Shield of Michigan |
| MBJ | Oregon/Idaho/Utah/Washington | Regence Blue-Cross Blue-Shield |
| MBK | New York | Empire Blue-Cross Blue-Shield of New York |
| MBL BCBS Prefix | California | Anthem Blue-Cross |
| MBM | Illinois | Blue-Cross Blue-Shield of Illinois |
| MBN | Michigan | Blue-Cross Blue-Shield of Michigan |
| MBO | Florida | Florida-Blue |
| MBP | Indiana | Anthem Blue-Cross Blue-Shield of Indiana |
| MBQ | - | Unallocated/Not Assigned |
| MBR | California | Anthem Blue-Cross |
| MBS | Maryland/District of Columbia/Northern Virginia | Carefirst Blue-Cross Blue-Shield |
| MBT | Missouri | Anthem Blue-Cross Blue-Shield of Missouri |
| MBU | Massachusetts | Blue-Cross Blue-Shield of Massachusetts |
| MBV | Maryland/District of Columbia/Northern Virginia | Carefirst Blue-Cross Blue-Shield |
| MBW | Ohio | Anthem Blue-Cross Blue-Shield of Ohio |
| MBX | South Carolina | Blue-Cross Blue-Shield of South Carolina |
| MBY | South Carolina | Blue-Cross Blue-Shield of South Carolina |
| MBZ | Maryland/District of Columbia/Northern Virginia | Carefirst Blue-Cross Blue-Shield |
| MCA | California | Blue-Shield of California |
| MCB | Kansas City | Blue-Cross Blue-Shield of Kansas City |
| MCC | Texas | Blue-Cross Blue-Shield of Texas |
| MCD | Illinois | Blue-Cross Blue-Shield of Illinois |
| MCE | Alaska | Premera Blue-Cross Blue-Shield of Alaska |
| MCF | Maryland/District of Columbia/Northern Virginia | Carefirst Blue-Cross Blue-Shield |
| MCG | Maryland/District of Columbia/Northern Virginia | Carefirst Blue-Cross Blue-Shield |
| MCH | Florida | Florida-Blue |
| MCI | Georgia | Anthem Blue-Cross Blue-Shield of Georgia |
| MCJ | West Virginia | Highmark Blue-Cross Blue-Shield of West Virginia |
| MCK | South Dakota/Iowa | Wellmark Blue-Cross Blue-Shield |
| MCL | South Dakota/Iowa | Wellmark Blue-Cross Blue-Shield |
| MCM | Arkansas | Arkansas Blue-Cross Blue-Shield |
| MCN | South Dakota/Iowa | Wellmark Blue-Cross Blue-Shield |
| MCO BCBS Prefix | Virginia | Anthem Blue-Cross Blue-Shield of Virginia |
| MCP | - | Unallocated/Not Assigned |
| MCQ | Illinois | Blue-Cross Blue-Shield of Illinois |
| MCR | Maryland/District of Columbia/Northern Virginia | Carefirst Blue-Cross Blue-Shield |
| MCS | Maryland/District of Columbia/Northern Virginia | Carefirst Blue-Cross Blue-Shield |
| MCT | South Dakota/Iowa | Wellmark Blue-Cross Blue-Shield |
| MCU | North Carolina | Blue-Cross Blue-Shield of North Carolina |
| MCV | South Dakota/Iowa | Wellmark Blue-Cross Blue-Shield |
| MCW | South Dakota/Iowa | Wellmark Blue-Cross Blue-Shield |
| MCX | Massachusetts | Blue-Cross Blue-Shield of Massachusetts |
| MCY | Virginia | Anthem Blue-Cross Blue-Shield of Virginia |
| MCZ | Indiana | Anthem Blue-Cross Blue-Shield of Indiana |
| MDA | Michigan | Blue-Cross Blue-Shield of Michigan |
| MDB | South Carolina | Blue-Cross Blue-Shield of South Carolina |
| MDC BCBS Prefix | Minnesota | Blue-Cross Blue-Shield of Minnesota |
| MDD | Maryland/District of Columbia/Northern Virginia | Carefirst Blue-Cross Blue-Shield |
| MDE | California | Anthem Blue-Cross |
| MDF | Pennsylvania | Independence Blue-Cross of Philadelphia and Southeastern Pennsylvania |
| MDG | Michigan | Blue-Cross Blue-Shield of Michigan |
| MDH | Rhode Island | Blue-Cross Blue-Shield of Rhode Island |
| MDI | South Dakota/Iowa | Wellmark Blue-Cross Blue-Shield |
| MDJ | Indiana | Anthem Blue-Cross Blue-Shield of Indiana |
| MDK | North Carolina | Blue-Cross Blue-Shield of North Carolina |
| MDL | - | Unallocated/Not Assigned |
| MDM | Maryland/District of Columbia/Northern Virginia | Carefirst Blue-Cross Blue-Shield |
| MDN | Wisconsin | Anthem Blue-Cross Blue-Shield of Wisconsin |
| MDO | - | Unallocated/Not Assigned |
| MDP | California | Blue-Shield of California |
| MDQ | Minnesota | Blue-Cross Blue-Shield of Minnesota |
| MDR | Wisconsin | Anthem Blue-Cross Blue-Shield of Wisconsin |
| MDS | Maryland/District of Columbia/Northern Virginia | Carefirst Blue-Cross Blue-Shield |
| MDT | Maryland/District of Columbia/Northern Virginia | Carefirst Blue-Cross Blue-Shield |
| MDU | South Dakota/Iowa | Wellmark Blue-Cross Blue-Shield |
| MDV | Louisiana | Blue-Cross Blue-Shield of Louisiana |
| MDW | South Dakota/Iowa | Wellmark Blue-Cross Blue-Shield |
| MDX | Illinois | Blue-Cross Blue-Shield of Illinois |
| MDY | Kansas City | Blue-Cross Blue-Shield of Kansas City |
| MDZ | Minnesota | Blue-Cross Blue-Shield of Minnesota |
| MEA | California | Blue-Shield of California |
| MEB | Maine | Anthem Blue-Cross Blue-Shield of Maine |
| MEC | Virginia | Anthem Blue-Cross Blue-Shield of Virginia |
| MED | Indiana | Anthem Blue-Cross Blue-Shield of Indiana |
| MEE | Virginia | Anthem Blue-Cross Blue-Shield of Virginia |
| MEF | - | Unallocated/Not Assigned |
| MEG | Georgia | Anthem Blue-Cross Blue-Shield of Georgia |
| MEH | - | Unallocated/Not Assigned |
| MEI | Michigan | Blue-Cross Blue-Shield of Michigan |
| MEJ | Maryland/District of Columbia/Northern Virginia | Carefirst Blue-Cross Blue-Shield |
| MEK | California | Blue-Shield of California |
| MEL | South Dakota/Iowa | Wellmark Blue-Cross Blue-Shield |
| MEM | South Dakota/Iowa | Wellmark Blue-Cross Blue-Shield |
| MEN | Maine | Anthem Blue-Cross Blue-Shield of Maine |
| MEO | California | Blue-Shield of California |
| MEP | Maine | Anthem Blue-Cross Blue-Shield of Maine |
| MEQ | California | Blue-Shield of California |
| MER | - | Unallocated/Not Assigned |
| MES | Oklahoma | Blue-Cross Blue-Shield of Oklahoma |
| MET | Nebraska | Blue-Cross Blue-Shield of Nebraska |
| MEU | Texas | Blue-Cross Blue-Shield of Texas |
| MEV | - | Unallocated/Not Assigned |
| MEW | Maine | Anthem Blue-Cross Blue-Shield of Maine |
| MEX | New Mexico | Blue-Cross Blue-Shield of New Mexico |
| MEY | Maine | Anthem Blue-Cross Blue-Shield of Maine |
| MEZ | New Mexico | Blue-Cross Blue-Shield of New Mexico |
| MFA | Illinois | Blue-Cross Blue-Shield of Illinois |
| MFB | South Dakota/Iowa | Wellmark Blue-Cross Blue-Shield |
| MFC | Georgia | Anthem Blue-Cross Blue-Shield of Georgia |
| MFD | Georgia | Anthem Blue-Cross Blue-Shield of Georgia |
| MFE | California | Anthem Blue-Cross |
| MFF | Oregon/Idaho/Utah/Washington | Regence Blue-Cross Blue-Shield |
| MFG | Ohio | Anthem Blue-Cross Blue-Shield of Ohio |
| MFH | Georgia | Anthem Blue-Cross Blue-Shield of Georgia |
| MFI | South Dakota/Iowa | Wellmark Blue-Cross Blue-Shield |
| MFJ | - | Unallocated/Not Assigned |
| MFK | Maryland/District of Columbia/Northern Virginia | Carefirst Blue-Cross Blue-Shield |
| MFL | Pennsylvania | Independence Blue-Cross of Philadelphia and Southeastern Pennsylvania |
| MFM | Georgia | Anthem Blue-Cross Blue-Shield of Georgia |
| MFN | Virginia | Anthem Blue-Cross Blue-Shield of Virginia |
| MFO | - | Unallocated/Not Assigned |
| MFP | Oregon/Idaho/Utah/Washington | Regence Blue-Cross Blue-Shield |
| MFQ | Virginia | Anthem Blue-Cross Blue-Shield of Virginia |
| MFR | - | Unallocated/Not Assigned |
| MFS | Maryland/District of Columbia/Northern Virginia | Carefirst Blue-Cross Blue-Shield |
| MFT | - | Unallocated/Not Assigned |
| MFU | South Dakota/Iowa | Wellmark Blue-Cross Blue-Shield |
| MFV | Illinois | Blue-Cross Blue-Shield of Illinois |
| MFW | California | Anthem Blue-Cross |
| MFX | Michigan | Blue-Cross Blue-Shield of Michigan |
| MFY | Minnesota | Blue-Cross Blue-Shield of Minnesota |
| MFZ | Illinois | Blue-Cross Blue-Shield of Illinois |
| MGA | California | Blue-Shield of California |
| MGB | Pennsylvania | Capital Blue-Cross of Pennsylvania |
| MGC | Illinois | Blue-Cross Blue-Shield of Illinois |
| MGD | Alaska | Premera Blue-Cross Blue-Shield of Alaska |
| MGE | Rhode Island | Blue-Cross Blue-Shield of Rhode Island |
| MGF | - | Unallocated/Not Assigned |
| MGG | California | Blue-Shield of California |
| MGH | - | Unallocated/Not Assigned |
| MGI | Pennsylvania | Highmark Blue-Cross Blue-Shield of Pennsylvania |
| MGJ | Missouri | Anthem Blue-Cross Blue-Shield of Missouri |
| MGK | South Dakota/Iowa | Wellmark Blue-Cross Blue-Shield |
| MGL | Pennsylvania | Independence Blue-Cross of Philadelphia and Southeastern Pennsylvania |
| MGM | Maryland/District of Columbia/Northern Virginia | Carefirst Blue-Cross Blue-Shield |
| MGN | South Carolina | Blue-Cross Blue-Shield of South Carolina |
| MGO | Michigan | Blue-Cross Blue-Shield of Michigan |
| MGP | South Dakota/Iowa | Wellmark Blue-Cross Blue-Shield |
| MGQ | - | Unallocated/Not Assigned |
| MGR | Michigan | Blue-Cross Blue-Shield of Michigan |
| MGS | Georgia | Anthem Blue-Cross Blue-Shield of Georgia |
| MGT | Oregon/Idaho/Utah/Washington | Regence Blue-Cross Blue-Shield |
| MGU | Virginia | Anthem Blue-Cross Blue-Shield of Virginia |
| MGV | South Carolina | Blue-Cross Blue-Shield of South Carolina |
| MGW | Arkansas | Arkansas Blue-Cross Blue-Shield |
| MGX | - | Unallocated/Not Assigned |
| MGY | California | Blue-Shield of California |
| MGZ | New Jersey | Horizon Blue-Cross Blue-Shield of New Jersey |
| MHA | Kansas City | Blue-Cross Blue-Shield of Kansas City |
| MHB | Texas | Blue-Cross Blue-Shield of Texas |
| MHC | Pennsylvania | Highmark Blue-Cross Blue-Shield of Pennsylvania |
| MHD | - | Unallocated/Not Assigned |
| MHE | - | Unallocated/Not Assigned |
| MHF | - | Unallocated/Not Assigned |
| MHG | California | Anthem Blue-Cross |
| MHH | Michigan | Blue-Cross Blue-Shield of Michigan |
| MHI | Georgia | Anthem Blue-Cross Blue-Shield of Georgia |
| MHJ | - | Unallocated/Not Assigned |
| MHK | South Dakota/Iowa | Wellmark Blue-Cross Blue-Shield |
| MHL | - | Unallocated/Not Assigned |
| MHM | Maryland/District of Columbia/Northern Virginia | Carefirst Blue-Cross Blue-Shield |
| MHN | Ohio | Anthem Blue-Cross Blue-Shield of Ohio |
| MHO | - | Unallocated/Not Assigned |
| MHP | New York | Empire Blue-Cross Blue-Shield of New York |
| MHQ | Georgia | Anthem Blue-Cross Blue-Shield of Georgia |
| MHR | Ohio | Anthem Blue-Cross Blue-Shield of Ohio |
| MHS | Kentucky | Anthem Blue-Cross Blue-Shield of Kentucky |
| MHT | Maryland/District of Columbia/Northern Virginia | Carefirst Blue-Cross Blue-Shield |
| MHU | - | Unallocated/Not Assigned |
| MHV | - | Unallocated/Not Assigned |
| MHW | Alabama | Blue-Cross Blue-Shield of Alabama |
| MHX | - | Unallocated/Not Assigned |
| MHY | California | Anthem Blue-Cross |
| MHZ | South Dakota/Iowa | Wellmark Blue-Cross Blue-Shield |
| MIA | California | Blue-Shield of California |
| MIB | Minnesota | Blue-Cross Blue-Shield of Minnesota |
| MIC | South Carolina | Blue-Cross Blue-Shield of South Carolina |
| MID | - | Unallocated/Not Assigned |
| MIE | Minnesota | Blue-Cross Blue-Shield of Minnesota |
| MIF | Ohio | Anthem Blue-Cross Blue-Shield of Ohio |
| MIG | Michigan | Blue-Cross Blue-Shield of Michigan |
| MIH | - | Unallocated/Not Assigned |
| MII | Kansas City | Blue-Cross Blue-Shield of Kansas City |
| MIJ | Michigan | Blue-Cross Blue-Shield of Michigan |
| MIK | - | Unallocated/Not Assigned |
| MIL | Massachusetts | Blue-Cross Blue-Shield of Massachusetts |
| MIM | Pennsylvania | Highmark Blue-Cross Blue-Shield of Pennsylvania |
| MIN | Alaska | Premera Blue-Cross Blue-Shield of Alaska |
| MIO | California | Blue-Shield of California |
| MIP | Idaho | Blue-Cross of Idaho |
| MIQ | Ohio | Anthem Blue-Cross Blue-Shield of Ohio |
| MIR | - | Unallocated/Not Assigned |
| MIS | Ohio | Anthem Blue-Cross Blue-Shield of Ohio |
| MIT | South Dakota/Iowa | Wellmark Blue-Cross Blue-Shield |
| MIU | South Carolina | Blue-Cross Blue-Shield of South Carolina |
| MIV | New York (Western) | Blue-Cross Blue-Shield of Western New York |
| MIW | Michigan | Blue-Cross Blue-Shield of Michigan |
| MIX | California | Blue-Shield of California |
| MIY | - | Unallocated/Not Assigned |
| MIZ | California | Blue-Shield of California |
| MJA | - | Unallocated/Not Assigned |
| MJB | Colorado | Anthem Blue-Cross Blue-Shield of Colorado |
| MJC | Texas | Blue-Cross Blue-Shield of Texas |
| MJD | Alabama | Blue-Cross Blue-Shield of Alabama |
| MJE | Michigan | Blue-Cross Blue-Shield of Michigan |
| MJF | Maryland/District of Columbia/Northern Virginia | Carefirst Blue-Cross Blue-Shield |
| MJG | Alaska | Premera Blue-Cross Blue-Shield of Alaska |
| MJH | Wisconsin | Anthem Blue-Cross Blue-Shield of Wisconsin |
| MJI | Maryland/District of Columbia/Northern Virginia | Carefirst Blue-Cross Blue-Shield |
| MJJ | Michigan | Blue-Cross Blue-Shield of Michigan |
| MJK | Maryland/District of Columbia/Northern Virginia | Carefirst Blue-Cross Blue-Shield |
| MJL | California | Anthem Blue-Cross |
| MJM | Pennsylvania | Highmark Blue-Cross Blue-Shield of Pennsylvania |
| MJN | Pennsylvania | Highmark Blue-Cross Blue-Shield of Pennsylvania |
| MJO | Connecticut | Anthem Blue-Cross Blue-Shield of Connecticut |
| MJP | South Dakota/Iowa | Wellmark Blue-Cross Blue-Shield |
| MJQ | California | Anthem Blue-Cross |
| MJR | Michigan | Blue-Cross Blue-Shield of Michigan |
| MJS | Tennessee | Blue-Cross Blue-Shield of Tennessee |
| MJT | Wisconsin | Anthem Blue-Cross Blue-Shield of Wisconsin |
| MJU | Michigan | Blue-Cross Blue-Shield of Michigan |
| MJV | Wisconsin | Anthem Blue-Cross Blue-Shield of Wisconsin |
| MJW | - | Unallocated/Not Assigned |
| MJX | Michigan | Blue-Cross Blue-Shield of Michigan |
| MJY | - | Unallocated/Not Assigned |
| MJZ | - | Unallocated/Not Assigned |
| MKA | South Dakota/Iowa | Wellmark Blue-Cross Blue-Shield |
| MKB | California | Blue-Shield of California |
| MKC | South Carolina | Blue-Cross Blue-Shield of South Carolina |
| MKD | Massachusetts | Blue-Cross Blue-Shield of Massachusetts |
| MKE | Tennessee | Blue-Cross Blue-Shield of Tennessee |
| MKF | - | Unallocated/Not Assigned |
| MKG | Ohio | Anthem Blue-Cross Blue-Shield of Ohio |
| MKH | Tennessee | Blue-Cross Blue-Shield of Tennessee |
| MKI | Tennessee | Blue-Cross Blue-Shield of Tennessee |
| MKJ | Ohio | Anthem Blue-Cross Blue-Shield of Ohio |
| MKK | California | Anthem Blue-Cross |
| MKL | Mississippi | Blue-Cross Blue-Shield of Mississippi |
| MKM | Maryland/District of Columbia/Northern Virginia | Carefirst Blue-Cross Blue-Shield |
| MKN | - | Unallocated/Not Assigned |
| MKO | Michigan | Blue-Cross Blue-Shield of Michigan |
| MKP | Michigan | Blue-Cross Blue-Shield of Michigan |
| MKQ | - | Unallocated/Not Assigned |
| MKR | Illinois | Blue-Cross Blue-Shield of Illinois |
| MKS | Massachusetts | Blue-Cross Blue-Shield of Massachusetts |
| MKT | South Dakota/Iowa | Wellmark Blue-Cross Blue-Shield |
| MKU | Alaska | Premera Blue-Cross Blue-Shield of Alaska |
| MKV | New Jersey | Horizon Blue-Cross Blue-Shield of New Jersey |
| MKW | South Dakota/Iowa | Wellmark Blue-Cross Blue-Shield |
| MKX | - | Unallocated/Not Assigned |
| MKY | New Jersey | Horizon Blue-Cross Blue-Shield of New Jersey |
| MKZ | Maryland/District of Columbia/Northern Virginia | Carefirst Blue-Cross Blue-Shield |
| MLA | South Dakota/Iowa | Wellmark Blue-Cross Blue-Shield |
| MLB | - | Unallocated/Not Assigned |
| MLC | - | Unallocated/Not Assigned |
| MLD | - | Unallocated/Not Assigned |
| MLE | Illinois | Blue-Cross Blue-Shield of Illinois |
| MLF | Maryland/District of Columbia/Northern Virginia | Carefirst Blue-Cross Blue-Shield |
| MLG | Pennsylvania | Highmark Blue-Cross Blue-Shield of Pennsylvania |
| MLH | South Carolina | Blue-Cross Blue-Shield of South Carolina |
| MLI | Pennsylvania | Independence Blue-Cross of Philadelphia and Southeastern Pennsylvania |
| MLJ | Maryland/District of Columbia/Northern Virginia | Carefirst Blue-Cross Blue-Shield |
| MLK | Virginia | Anthem Blue-Cross Blue-Shield of Virginia |
| MLL | California | Blue-Shield of California |
| MLM | Pennsylvania | Highmark Blue-Cross Blue-Shield of Pennsylvania |
| MLN | California | Blue-Shield of California |
| MLO | New York (Western) | Blue-Cross Blue-Shield of Western New York |
| MLP | Virginia | Anthem Blue-Cross Blue-Shield of Virginia |
| MLQ | Minnesota | Blue-Cross Blue-Shield of Minnesota |
| MLR | Massachusetts | Blue-Cross Blue-Shield of Massachusetts |
| MLS | - | Unallocated/Not Assigned |
| MLT | Nebraska | Blue-Cross Blue-Shield of Nebraska |
| MLU | Minnesota | Blue-Cross Blue-Shield of Minnesota |
| MLV | Minnesota | Blue-Cross Blue-Shield of Minnesota |
| MLW | - | Unallocated/Not Assigned |
| MLX | Idaho | Blue-Cross of Idaho |
| MLY | Alaska | Premera Blue-Cross Blue-Shield of Alaska |
| MLZ | Rhode Island | Blue-Cross Blue-Shield of Rhode Island |
| MMA | New York | Empire Blue-Cross Blue-Shield of New York |
| MMB | Maryland/District of Columbia/Northern Virginia | Carefirst Blue-Cross Blue-Shield |
| MMC | Georgia | Anthem Blue-Cross Blue-Shield of Georgia |
| MMD | Alaska | Premera Blue-Cross Blue-Shield of Alaska |
| MME | Maryland/District of Columbia/Northern Virginia | Carefirst Blue-Cross Blue-Shield |
| MMF | New York | Excellus Blue-Cross Blue-Shield of New York |
| MMG | Mississippi | Blue-Cross Blue-Shield of Mississippi |
| MMH | New York | Empire Blue-Cross Blue-Shield of New York |
| MMI | Pennsylvania | Independence Blue-Cross of Philadelphia and Southeastern Pennsylvania |
| MMJ | Michigan | Blue-Cross Blue-Shield of Michigan |
| MMK | Illinois | Blue-Cross Blue-Shield of Illinois |
| MML | Illinois | Blue-Cross Blue-Shield of Illinois |
| MMM | Minnesota | Blue-Cross Blue-Shield of Minnesota |
| MMN | Minnesota | Blue-Cross Blue-Shield of Minnesota |
| MMO | Michigan | Blue-Cross Blue-Shield of Michigan |
| MMP | Georgia | Anthem Blue-Cross Blue-Shield of Georgia |
| MMQ | Indiana | Anthem Blue-Cross Blue-Shield of Indiana |
| MMR | Massachusetts | Blue-Cross Blue-Shield of Massachusetts |
| MMS | Ohio | Anthem Blue-Cross Blue-Shield of Ohio |
| MMT | California | Blue-Shield of California |
| MMU | Illinois | Blue-Cross Blue-Shield of Illinois |
| MMV | Ohio | Anthem Blue-Cross Blue-Shield of Ohio |
| MMW | Illinois | Blue-Cross Blue-Shield of Illinois |
| MMX | Alabama | Blue-Cross Blue-Shield of Alabama |
| MMY | Indiana | Anthem Blue-Cross Blue-Shield of Indiana |
| MMZ | South Dakota/Iowa | Wellmark Blue-Cross Blue-Shield |
| MNA | Minnesota | Blue-Cross Blue-Shield of Minnesota |
| MNB | Massachusetts | Blue-Cross Blue-Shield of Massachusetts |
| MNC | California | Anthem Blue-Cross |
| MND | Wisconsin | Anthem Blue-Cross Blue-Shield of Wisconsin |
| MNE | Wisconsin | Anthem Blue-Cross Blue-Shield of Wisconsin |
| MNF | Pennsylvania | Independence Blue-Cross of Philadelphia and Southeastern Pennsylvania |
| MNG | Tennessee | Blue-Cross Blue-Shield of Tennessee |
| MNH | Virginia | Anthem Blue-Cross Blue-Shield of Virginia |
| MNI | - | Unallocated/Not Assigned |
| MNJ | Ohio | Anthem Blue-Cross Blue-Shield of Ohio |
| MNK | Ohio | Anthem Blue-Cross Blue-Shield of Ohio |
| MNL | - | Unallocated/Not Assigned |
| MNM | - | Unallocated/Not Assigned |
| MNN | Pennsylvania | Highmark Blue-Cross Blue-Shield of Pennsylvania |
| MNO | - | Unallocated/Not Assigned |
| MNP | California | Blue-Shield of California |
| MNQ | Minnesota | Blue-Cross Blue-Shield of Minnesota |
| MNR | Minnesota | Blue-Cross Blue-Shield of Minnesota |
| MNS | Kentucky | Anthem Blue-Cross Blue-Shield of Kentucky |
| MNT | Illinois | Blue-Cross Blue-Shield of Illinois |
| MNU | North Carolina | Blue-Cross Blue-Shield of North Carolina |
| MNV | South Carolina | Blue-Cross Blue-Shield of South Carolina |
| MNW | Alaska | Premera Blue-Cross Blue-Shield of Alaska |
| MNX | Illinois | Blue-Cross Blue-Shield of Illinois |
| MNY | Alaska | Premera Blue-Cross of Alaska |
| MNZ | South Dakota/Iowa | Wellmark Blue-Cross Blue-Shield |
| MOA | - | Unallocated/Not Assigned |
| MOB | - | Unallocated/Not Assigned |
| MOC | Georgia | Anthem Blue-Cross Blue-Shield of Georgia |
| MOD | Massachusetts | Blue-Cross Blue-Shield of Massachusetts |
| MOE | Illinois | Blue-Cross Blue-Shield of Illinois |
| MOF | California | Blue-Shield of California |
| MOG | New York (Western) | Blue-Cross Blue-Shield of Western New York |
| MOH | - | Unallocated/Not Assigned |
| MOI | Massachusetts | Blue-Cross Blue-Shield of Massachusetts |
| MOJ | Ohio | Anthem Blue-Cross Blue-Shield of Ohio |
| MOK | Pennsylvania | Independence Blue-Cross of Philadelphia and Southeastern Pennsylvania |
| MOL | - | Unallocated/Not Assigned |
| MOM | - | Unallocated/Not Assigned |
| MON | - | Unallocated/Not Assigned |
| MOO | - | Unallocated/Not Assigned |
| MOP | - | Unallocated/Not Assigned |
| MOQ | Pennsylvania | Independence Blue-Cross of Philadelphia and Southeastern Pennsylvania |
| MOR | Alaska | Premera Blue-Cross Blue-Shield of Alaska |
| MOS | California | Blue-Shield of California |
| MOT | - | Unallocated/Not Assigned |
| MOU | Michigan | Blue-Cross Blue-Shield of Michigan |
| MOV | Arkansas | Arkansas Blue-Cross Blue-Shield |
| MOW | Kentucky | Anthem Blue-Cross Blue-Shield of Kentucky |
| MOX | - | Unallocated/Not Assigned |
| MOY | South Dakota/Iowa | Wellmark Blue-Cross Blue-Shield |
| MOZ | - | Unallocated/Not Assigned |
| MPA | Ohio | Anthem Blue-Cross Blue-Shield of Ohio |
| MPB | Georgia | Anthem Blue-Cross Blue-Shield of Georgia |
| MPC | Rhode Island | Blue-Cross Blue-Shield of Rhode Island |
| MPD | Texas | Blue-Cross Blue-Shield of Texas |
| MPE | Michigan | Blue-Cross Blue-Shield of Michigan |
| MPF | New York | Excellus Blue-Cross Blue-Shield of New York |
| MPG | Pennsylvania | Independence Blue-Cross of Philadelphia and Southeastern Pennsylvania |
| MPH | New York | Empire Blue-Cross Blue-Shield of New York |
| MPI BCBS Prefix | California | Anthem Blue-Cross |
| MPJ | South Carolina | Blue-Cross Blue-Shield of South Carolina |
| MPK | - | Unallocated/Not Assigned |
| MPL | Illinois | Blue-Cross Blue-Shield of Illinois |
| MPM | New York (Northeastern) | Blue-Shield of Northeastern New York |
| MPN | South Dakota/Iowa | Wellmark Blue-Cross Blue-Shield |
| MPO | Alabama | Blue-Cross Blue-Shield of Alabama |
| MPP | Wisconsin | Anthem Blue-Cross Blue-Shield of Wisconsin |
| MPQ | Minnesota | Blue-Cross Blue-Shield of Minnesota |
| MPR | California | Anthem Blue-Cross |
| MPS | Georgia | Anthem Blue-Cross Blue-Shield of Georgia |
| MPT | Minnesota | Blue-Cross Blue-Shield of Minnesota |
| MPU | Ohio | Anthem Blue-Cross Blue-Shield of Ohio |
| MPV | Georgia | Anthem Blue-Cross Blue-Shield of Georgia |
| MPW | Ohio | Anthem Blue-Cross Blue-Shield of Ohio |
| MPX | Minnesota | Blue-Cross Blue-Shield of Minnesota |
| MPY | Florida | Florida-Blue |
| MPZ | - | Unallocated/Not Assigned |
| MQA | Michigan | Blue-Cross Blue-Shield of Michigan |
| MQB | - | Unallocated/Not Assigned |
| MQC | - | Unallocated/Not Assigned |
| MQD | Maryland/District of Columbia/Northern Virginia | Carefirst Blue-Cross Blue-Shield |
| MQE | Georgia | Anthem Blue-Cross Blue-Shield of Georgia |
| MQF | - | Unallocated/Not Assigned |
| MQG | - | Unallocated/Not Assigned |
| MQH | Michigan | Blue-Cross Blue-Shield of Michigan |
| MQI | South Dakota/Iowa | Wellmark Blue-Cross Blue-Shield |
| MQJ | Michigan | Blue-Cross Blue-Shield of Michigan |
| MQK | Michigan | Blue-Cross Blue-Shield of Michigan |
| MQL | Michigan | Blue-Cross Blue-Shield of Michigan |
| MQM | - | Unallocated/Not Assigned |
| MQN | - | Unallocated/Not Assigned |
| MQO | Michigan | Blue-Cross Blue-Shield of Michigan |
| MQP | - | Unallocated/Not Assigned |
| MQQ | Idaho | Blue-Cross of Idaho |
| MQR | Pennsylvania | Highmark Blue-Cross Blue-Shield of Pennsylvania |
| MQS | - | Unallocated/Not Assigned |
| MQT | - | Unallocated/Not Assigned |
| MQU | Wisconsin | Anthem Blue-Cross Blue-Shield of Wisconsin |
| MQV | Nebraska | Blue-Cross Blue-Shield of Nebraska |
| MQW | Michigan | Blue-Cross Blue-Shield of Michigan |
| MQX | California | Anthem Blue-Cross |
| MQY | - | Unallocated/Not Assigned |
| MQZ | California | Anthem Blue-Cross |
| MRA | - | Unallocated/Not Assigned |
| MRB | - | Unallocated/Not Assigned |
| MRC | Illinois | Blue-Cross Blue-Shield of Illinois |
| MRD | - | Unallocated/Not Assigned |
| MRE | South Dakota/Iowa | Wellmark Blue-Cross Blue-Shield |
| MRF | Michigan | Blue-Cross Blue-Shield of Michigan |
| MRG | Illinois | Blue-Cross Blue-Shield of Illinois |
| MRH | Wisconsin | Anthem Blue-Cross Blue-Shield of Wisconsin |
| MRI | - | Unallocated/Not Assigned |
| MRJ | Maryland/District of Columbia/Northern Virginia | Carefirst Blue-Cross Blue-Shield |
| MRK | Massachusetts | Blue-Cross Blue-Shield of Massachusetts |
| MRL | South Dakota/Iowa | Wellmark Blue-Cross Blue-Shield |
| MRM | Kansas City | Blue-Cross Blue-Shield of Kansas City |
| MRN | Wisconsin | Anthem Blue-Cross Blue-Shield of Wisconsin |
| MRO | - | Unallocated/Not Assigned |
| MRP | Wisconsin | Anthem Blue-Cross Blue-Shield of Wisconsin |
| MRQ | Ohio | Anthem Blue-Cross Blue-Shield of Ohio |
| MRR | Minnesota | Blue-Cross Blue-Shield of Minnesota |
| MRS | South Dakota/Iowa | Wellmark Blue-Cross Blue-Shield |
| MRT | Texas | Blue-Cross Blue-Shield of Texas |
| MRU | Pennsylvania | Highmark Blue-Cross Blue-Shield of Pennsylvania |
| MRV | California | Anthem Blue-Cross |
| MRW | Illinois | Blue-Cross Blue-Shield of Illinois |
| MRX | Wisconsin | Anthem Blue-Cross Blue-Shield of Wisconsin |
| MRY | Alabama | Blue-Cross Blue-Shield of Alabama |
| MRZ | Illinois | Blue-Cross Blue-Shield of Illinois |
| MSA | Alabama | Blue-Cross Blue-Shield of Alabama |
| MSB | South Dakota/Iowa | Wellmark Blue-Cross Blue-Shield |
| MSC | Alabama | Blue-Cross Blue-Shield of Alabama |
| MSD | Pennsylvania | Independence Blue-Cross of Philadelphia and Southeastern Pennsylvania |
| MSE | Michigan | Blue-Cross Blue-Shield of Michigan |
| MSF | New York | Empire Blue-Cross Blue-Shield of New York |
| MSG | Michigan | Blue-Cross Blue-Shield of Michigan |
| MSH | Michigan | Blue-Cross Blue-Shield of Michigan |
| MSI | Oregon/Idaho/Utah/Washington | Regence Blue-Cross Blue-Shield |
| MSJ BCBS Prefix | Alaska | Premera Blue-Cross Blue-Shield of Alaska |
| MSK | Massachusetts | Blue-Cross Blue-Shield of Massachusetts |
| MSL | - | Unallocated/Not Assigned |
| MSM | Maryland/District of Columbia/Northern Virginia | Carefirst Blue-Cross Blue-Shield |
| MSN | Ohio | Anthem Blue-Cross Blue-Shield of Ohio |
| MSO | - | Unallocated/Not Assigned |
| MSP | Alaska | Premera Blue-Cross Blue-Shield of Alaska |
| MSQ | Alaska | Premera Blue-Cross Blue-Shield of Alaska |
| MSR | Michigan | Blue-Cross Blue-Shield of Michigan |
| MSS | Virginia | Anthem Blue-Cross Blue-Shield of Virginia |
| MST | Alaska | Premera Blue-Cross Blue-Shield of Alaska |
| MSU | Ohio | Anthem Blue-Cross Blue-Shield of Ohio |
| MSV | Alabama | Blue-Cross Blue-Shield of Alabama |
| MSW | Illinois | Blue-Cross Blue-Shield of Illinois |
| MSX | - | Unallocated/Not Assigned |
| MSY | North Carolina | Blue-Cross Blue-Shield of North Carolina |
| MSZ | California | Anthem Blue-Cross |
| MTA | Virginia | Anthem Blue-Cross Blue-Shield of Virginia |
| MTB | South Dakota/Iowa | Wellmark Blue-Cross Blue-Shield |
| MTC | Virginia | Anthem Blue-Cross Blue-Shield of Virginia |
| MTD | Alaska | Premera Blue-Cross Blue-Shield of Alaska |
| MTE | California | Blue-Shield of California |
| MTF | Georgia | Anthem Blue-Cross Blue-Shield of Georgia |
| MTG | - | Unallocated/Not Assigned |
| MTH | South Dakota/Iowa | Wellmark Blue-Cross Blue-Shield |
| MTI | California | Blue-Shield of California |
| MTJ | - | Unallocated/Not Assigned |
| MTK | - | Unallocated/Not Assigned |
| MTL | - | Unallocated/Not Assigned |
| MTM | - | Unallocated/Not Assigned |
| MTN BCBS Prefix | Massachusetts | Blue-Cross Blue-Shield of Massachusetts |
| MTO | California | Blue-Shield of California |
| MTP | Massachusetts | Blue-Cross Blue-Shield of Massachusetts |
| MTQ | - | Unallocated/Not Assigned |
| MTR | Tennessee | Blue-Cross Blue-Shield of Tennessee |
| MTS | Maryland/District of Columbia/Northern Virginia | Carefirst Blue-Cross Blue-Shield |
| MTT | California | Blue-Shield of California |
| MTU | Alaska | Premera Blue-Cross of Alaska |
| MTV | Indiana | Anthem Blue-Cross Blue-Shield of Indiana |
| MTW | Ohio | Anthem Blue-Cross Blue-Shield of Ohio |
| MTX | Maryland/District of Columbia/Northern Virginia | Carefirst Blue-Cross Blue-Shield |
| MTY | California | Anthem Blue-Cross |
| MTZ | Illinois | Blue-Cross Blue-Shield of Illinois |
| MUA | Texas | Blue-Cross Blue-Shield of Texas |
| MUB | Virginia | Anthem Blue-Cross Blue-Shield of Virginia |
| MUC | South Dakota/Iowa | Wellmark Blue-Cross Blue-Shield |
| MUD | South Dakota/Iowa | Wellmark Blue-Cross Blue-Shield |
| MUE | South Dakota/Iowa | Wellmark Blue-Cross Blue-Shield |
| MUF | Wisconsin | Anthem Blue-Cross Blue-Shield of Wisconsin |
| MUG | Arkansas | Arkansas Blue-Cross Blue-Shield |
| MUH | Idaho | Blue-Cross of Idaho |
| MUI | - | Unallocated/Not Assigned |
| MUJ | Indiana | Anthem Blue-Cross Blue-Shield of Indiana |
| MUK | Wisconsin | Anthem Blue-Cross Blue-Shield of Wisconsin |
| MUL | - | Unallocated/Not Assigned |
| MUM | Arizona | Blue-Cross Blue-Shield of Arizona |
| MUN | Illinois | Blue-Cross Blue-Shield of Illinois |
| MUO | Wisconsin | Anthem Blue-Cross Blue-Shield of Wisconsin |
| MUP | South Carolina | Blue-Cross Blue-Shield of South Carolina |
| MUQ | Alaska | Premera Blue-Cross of Alaska |
| MUR | Michigan | Blue-Cross Blue-Shield of Michigan |
| MUS | Illinois | Blue-Cross Blue-Shield of Illinois |
| MUT | Minnesota | Blue-Cross Blue-Shield of Minnesota |
| MUU | - | Unallocated/Not Assigned |
| MUV | Maryland/District of Columbia/Northern Virginia | Carefirst Blue-Cross Blue-Shield |
| MUW | Pennsylvania | Highmark Blue-Cross Blue-Shield of Pennsylvania |
| MUX | South Dakota/Iowa | Wellmark Blue-Cross Blue-Shield |
| MUY | Alabama | Blue-Cross Blue-Shield of Alabama |
| MUZ | Michigan | Blue-Cross Blue-Shield of Michigan |
| MVA | Montana | Blue-Cross Blue-Shield of Montana |
| MVB | Vermont | Blue-Cross Blue-Shield of Vermont |
| MVC | - | Unallocated/Not Assigned |
| MVD | Alaska | Premera Blue-Cross Blue-Shield of Alaska |
| MVE | Massachusetts | Blue-Cross Blue-Shield of Massachusetts |
| MVF | New York | Empire Blue-Cross Blue-Shield of New York |
| MVG | Minnesota | Blue-Cross Blue-Shield of Minnesota |
| MVH | South Dakota/Iowa | Wellmark Blue-Cross Blue-Shield |
| MVI | - | Unallocated/Not Assigned |
| MVJ | California | Blue-Shield of California |
| MVK | Georgia | Anthem Blue-Cross Blue-Shield of Georgia |
| MVL | Massachusetts | Blue-Cross Blue-Shield of Massachusetts |
| MVM | Alabama | Blue-Cross Blue-Shield of Alabama |
| MVN | New York | Empire Blue-Cross Blue-Shield of New York |
| MVO | Idaho | Blue-Cross of Idaho |
| MVP | Maryland/District of Columbia/Northern Virginia | Carefirst Blue-Cross Blue-Shield |
| MVQ | Idaho | Blue-Cross of Idaho |
| MVR | Pennsylvania | Highmark Blue-Cross Blue-Shield of Pennsylvania |
| MVS | - | Unallocated/Not Assigned |
| MVT | Minnesota | Blue-Cross Blue-Shield of Minnesota |
| MVU | Indiana | Anthem Blue-Cross Blue-Shield of Indiana |
| MVV | South Dakota/Iowa | Wellmark Blue-Cross Blue-Shield |
| MVW | - | Unallocated/Not Assigned |
| MVX | South Carolina | Blue-Cross Blue-Shield of South Carolina |
| MVY | Ohio | Anthem Blue-Cross Blue-Shield of Ohio |
| MVZ | Texas | Blue-Cross Blue-Shield of Texas |
| MWA | Illinois | Blue-Cross Blue-Shield of Illinois |
| MWB | - | Unallocated/Not Assigned |
| MWC | - | Unallocated/Not Assigned |
| MWD | Maryland/District of Columbia/Northern Virginia | Carefirst Blue-Cross Blue-Shield |
| MWE | Wisconsin | Anthem Blue-Cross Blue-Shield of Wisconsin |
| MWF | Illinois | Blue-Cross Blue-Shield of Illinois |
| MWG | Minnesota | Blue-Cross Blue-Shield of Minnesota |
| MWH | Illinois | Blue-Cross Blue-Shield of Illinois |
| MWI | - | Unallocated/Not Assigned |
| MWJ | New Jersey | Horizon Blue-Cross Blue-Shield of New Jersey |
| MWK | New Jersey | Horizon Blue-Cross Blue-Shield of New Jersey |
| MWL | Illinois | Blue-Cross Blue-Shield of Illinois |
| MWM | Wisconsin | Anthem Blue-Cross Blue-Shield of Wisconsin |
| MWN | Illinois | Blue-Cross Blue-Shield of Illinois |
| MWO | Pennsylvania | Independence Blue-Cross of Philadelphia and Southeastern Pennsylvania |
| MWP | Massachusetts | Blue-Cross Blue-Shield of Massachusetts |
| MWQ | - | Unallocated/Not Assigned |
| MWR | Kansas City | Blue-Cross Blue-Shield of Kansas City |
| MWS | - | Unallocated/Not Assigned |
| MWT | - | Unallocated/Not Assigned |
| MWU | Wisconsin | Anthem Blue-Cross Blue-Shield of Wisconsin |
| MWV | Wisconsin | Anthem Blue-Cross Blue-Shield of Wisconsin |
| MWW | Nevada | Anthem Blue-Cross Blue-Shield of Nevada |
| MWX | Alabama | Blue-Cross Blue-Shield of Alabama |
| MWY | - | Unallocated/Not Assigned |
| MWZ | Pennsylvania | Independence Blue-Cross of Philadelphia and Southeastern Pennsylvania |
| MXA | California | Anthem Blue-Cross |
| MXB | - | Unallocated/Not Assigned |
| MXC | - | Unallocated/Not Assigned |
| MXD | Texas | Blue-Cross Blue-Shield of Texas |
| MXE | Texas | Blue-Cross Blue-Shield of Texas |
| MXF | New York | Empire Blue-Cross Blue-Shield of New York |
| MXG | - | Unallocated/Not Assigned |
| MXH BCBS Prefix | Maryland/District of Columbia/Northern Virginia | Carefirst Blue-Cross Blue-Shield |
| MXI | California | Blue-Shield of California |
| MXJ | - | Unallocated/Not Assigned |
| MXK | Pennsylvania | Capital Blue-Cross of Pennsylvania |
| MXL | South Dakota/Iowa | Wellmark Blue-Cross Blue-Shield |
| MXM | South Dakota/Iowa | Wellmark Blue-Cross Blue-Shield |
| MXN | Massachusetts | Blue-Cross Blue-Shield of Massachusetts |
| MXO | South Dakota/Iowa | Wellmark Blue-Cross Blue-Shield |
| MXP | Massachusetts | Blue-Cross Blue-Shield of Massachusetts |
| MXQ | New York | Empire Blue-Cross Blue-Shield of New York |
| MXR | California | Anthem Blue-Cross |
| MXS | Georgia | Anthem Blue-Cross Blue-Shield of Georgia |
| MXT | - | Unallocated/Not Assigned |
| MXU | Connecticut | Anthem Blue-Cross Blue-Shield of Connecticut |
| MXV | Idaho | Blue-Cross of Idaho |
| MXW | Idaho | Blue-Cross of Idaho |
| MXX | - | Unallocated/Not Assigned |
| MXY | Massachusetts | Blue-Cross Blue-Shield of Massachusetts |
| MXZ | Alaska | Premera Blue-Cross Blue-Shield of Alaska |
| MYA | - | Unallocated/Not Assigned |
| MYB | Oregon/Idaho/Utah/Washington | Regence Blue-Cross Blue-Shield |
| MYC | - | Unallocated/Not Assigned |
| MYD | Massachusetts | Blue-Cross Blue-Shield of Massachusetts |
| MYE | Ohio | Anthem Blue-Cross Blue-Shield of Ohio |
| MYF | New York | Empire Blue-Cross Blue-Shield of New York |
| MYG | South Dakota/Iowa | Wellmark Blue-Cross Blue-Shield |
| MYH | Massachusetts | Blue-Cross Blue-Shield of Massachusetts |
| MYI | Massachusetts | Blue-Cross Blue-Shield of Massachusetts |
| MYJ | - | Unallocated/Not Assigned |
| MYK | Massachusetts | Blue-Cross Blue-Shield of Massachusetts |
| MYL | Massachusetts | Blue-Cross Blue-Shield of Massachusetts |
| MYM | Ohio | Anthem Blue-Cross Blue-Shield of Ohio |
| MYN | Ohio | Anthem Blue-Cross Blue-Shield of Ohio |
| MYO | - | Unallocated/Not Assigned |
| MYP | - | Unallocated/Not Assigned |
| MYQ | Massachusetts | Blue-Cross Blue-Shield of Massachusetts |
| MYR | Alabama | Blue-Cross Blue-Shield of Alabama |
| MYS | Massachusetts | Blue-Cross Blue-Shield of Massachusetts |
| MYT | Michigan | Blue-Cross Blue-Shield of Michigan |
| MYU | Massachusetts | Blue-Cross Blue-Shield of Massachusetts |
| MYV | - | Unallocated/Not Assigned |
| MYW | Maryland/District of Columbia/Northern Virginia | Carefirst Blue-Cross Blue-Shield |
| MYX | Oklahoma | Blue-Cross Blue-Shield of Oklahoma |
| MYY BCBS Prefix | Maryland/District of Columbia/Northern Virginia | Carefirst Blue-Cross Blue-Shield |
| MYZ | Massachusetts | Blue-Cross Blue-Shield of Massachusetts |
| MZA | South Dakota/Iowa | Wellmark Blue-Cross Blue-Shield |
| MZB | Pennsylvania | Highmark Blue-Cross Blue-Shield of Pennsylvania |
| MZC | Rhode Island | Blue-Cross Blue-Shield of Rhode Island |
| MZD | Illinois | Blue-Cross Blue-Shield of Illinois |
| MZE | Massachusetts | Blue-Cross Blue-Shield of Massachusetts |
| MZF | - | Unallocated/Not Assigned |
| MZG | Illinois | Blue-Cross Blue-Shield of Illinois |
| MZH | Arizona | Blue-Cross Blue-Shield of Arizona |
| MZI | California | Blue-Shield of California |
| MZJ | Wisconsin | Anthem Blue-Cross Blue-Shield of Wisconsin |
| MZK | Virginia | Anthem Blue-Cross Blue-Shield of Virginia |
| MZL | Alabama | Blue-Cross Blue-Shield of Alabama |
| MZM | Minnesota | Blue-Cross Blue-Shield of Minnesota |
| MZN | North Carolina | Blue-Cross Blue-Shield of North Carolina |
| MZO | Michigan | Blue-Cross Blue-Shield of Michigan |
| MZP | Michigan | Blue-Cross Blue-Shield of Michigan |
| MZQ | Minnesota | Blue-Cross Blue-Shield of Minnesota |
| MZR | Minnesota | Blue-Cross Blue-Shield of Minnesota |
| MZS | - | Unallocated/Not Assigned |
| MZT | Minnesota | Blue-Cross Blue-Shield of Minnesota |
| MZU | Florida | Florida-Blue |
| MZV | - | Unallocated/Not Assigned |
| MZW | Minnesota | Blue-Cross Blue-Shield of Minnesota |
| MZX | Minnesota | Blue-Cross Blue-Shield of Minnesota |
| MZY | Michigan | Blue-Cross Blue-Shield of Michigan |
| MZZ | Minnesota | Blue-Cross Blue-Shield of Minnesota |