AT05, AT99, AT26 Adjustment Remark Codes and Billing Instructions


AT 05, AT99, AT26 adjustment remark codes

Billing instruction for Ambulance Billing

Note : When using “AT05”, indicating a Medicare payment, please remember to properly complete and attach the "Supplemental Medicare Attachment for Providers" form (MA-539).
When using “AT10”, indicating a payment from a Commercial Insurance, please remember to properly complete and attach the "Supplemental Attachment for Commercial Insurance for Providers" form (MA-538).

Attachment Type Code “AT99” indicates that remarks are attached. Remarks must be placed on an 8-1/2" x 11" sheet of white paper clipped to your claim. Remember, when you have a remarks sheet attached, include your provider number and the recipient’s number on the top left-hand corner of the page (i.e., Enter AT26, AT99 if billing for newborns that have temporary eligibility under the mother’s recipient number. On the remarks sheet, include the mother’s full name, date of birth, and social security number.).

If submitting an adjustment to a previously paid CMS-1500 claim (as referenced in Block 22), you must paper clip an 8-1/2" by 11" sheet of paper to the paper claim form containing an explanation as to why you are submitting the claim adjustment.

For a complete listing and description of Attachment Type Codes, please refer to the  CMS-
1500 Claim Form Desk Reference, located in Appendix A of the handbook.

Qualified Small BusinessesQualified small businesses must always enter the following message in Block 19 (Reserved for Local Use) of the CMS-1500, in addition to any applicable attachment type codes:
“(Name of Vendor) is a qualified small business concern as defined in 4 Pa Code §2.32.”

*Note: If the recipient has coverage through Medicare Part B and MA, this claim should automatically cross over to MA for payment of any applicable deductible or co-insurance. If the claim does not cross over from Medicare and you are submitting the claim directly to MA, enter AT05 in Block 19 and attach a completed "Supplemental Medicare Attachment for Providers" form to the claim.