CMS 1500 field and descriptions

Block 8. Check the appropriate box for the patient’s marital status and whether employed or a student.



Block 9. Enter the last name, first name, and middle initial of the enrollee in a Medigap policy, if it is different from that shown in Block 2. Otherwise, enter the word SAME. If no Medigap benefits are assigned, leave blank. This field may be used in the future for supplemental insurance plans.

 Block 9a. Enter the policy and/or group number of the Medigap insured preceded by Medigap

Block 9b. Enter the Medigap insurer’s birth date and sex.


Block 9c. Leave blank if a Medigap *PAYERID is entered in Block 9d. Otherwise, enter the claims processing address of the Medigap insurer. Use an abbreviated street address, two-letter postal code, and zip code copied from the Medigap insurer’s Medigap identification card.

For example:

1257 Anywhere Street

Baltimore, Maryland 21204

is shown as “1257 anywhere St MD 21204.”

Block 9d. Enter the nine-digit PAYERID number of the Medigap insurer. If no PAYERID number exists, then enter the Medigap insurance program or plan name.

Block 10a. Check “YES” or “NO” to indicate whether employment, auto liability, or Thru other accident involvement applies to one or more of the services described Block 10c. in Block 24. Enter the state postal code. Any Block checked “YES,” indicates there may be other insurance primary to Medicare. Identify primary insurance information in Block 11.



Block 10d. Use this Block exclusively for Medicaid (MCD) information. If the patient is entitled to Medicaid, enter the patient’s Medicaid number preceded by “MCD.”

Block 11. THIS BLOCK MUST BE COMPLETED. BY COMPLETING THIS BLOCK, THE PHYSICIAN/SUPPLIER ACKNOWLEDGES HAVING MADE A GOOD FAITH EFFORT TO DETERMINE WHETHER MEDICARE IS THE PRIMARY OR SECONDARY PAYER.



If there is insurance primary to Medicare, enter the insured’s policy or group number and proceed to Blocks 11a - 11c.

Block 11a. Enter the insured’s birth date and sex if different from Block 3.


Block 11b. Enter employer’s name, if applicable. If there is a change in the insured’s insurance status, e.g., retired, enter the retirement date preceded by the word “RETIRED.”

Block 11c. Enter the nine-digit PAYERID number of the primary insurer. If no PAYERID number exists, then enter the complete primary payer’s program or plan name. If the primary payer’s EOB does not contain the claims processing address, record the primary payer’s claims processing address directly on the EOB.

Block 11d. Leave it blank. Not required by Medicare.