AT and GA Modifiers When Billing CMT and Non-covered Codes to Medicare

by  Brandy Brimhall, CPC CPCO CMCO CPMA QCC
December 13th, 2017


We have a question regarding using modifiers when billing CMT and non-covered codes to Medicare. For several years we have used ATGA to bill for active care for CMT codes 98940-98942  (Ex: 98941-ATGA). AT for "Active" and "GA" to show they'd signed an ABN. We've never had any rejections from our electronic clearing house, nor from Medicare. Our concern is we were told today, by our state association, that we should never bill GA with AT. But don't we need to show they've signed an ABN so we can collect from the patient "just in case" Medicare doesn't pay? If the CMT is for a maintenance visit, should we use the GA (98941-GA), so we can collect from the patient?


AT GA are not permitted to be used together by Medicare.  Medicare prohibits the use of the ABN form if the patient is in active/corrective care (AT).  

Medicare will penalize for inappropriate use of the ABN.  They do not allow the ABN to be used for:

  1. Covered services that are expected to be paid
  2. "Blanket" ABN purposes (getting the ABN signed just in case)
  3. Routine use (getting ABN's signed randomly just because)

ABN's for mandatory use may ONLY be implemented as the patient begins maintenance care or if covered services (9894-) are not expected to be paid.

AT and GA Modifiers When Billing CMT and Non-covered Codes to Medicare. (2017, December 13). Find-A-Code Articles. Retrieved from

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