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using mod GA vs GX when billing Medicare

Albany, NY
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I have used modifier GX on an L code to Medicare knowing that the procedure would deny. I was expecting that the denial would hold pt responsible however it rejected the same way it would have without the modifier (contractual obligation); will the GX modifier affect my claim if a 2ndary payor is involved? Will they consider and pay? Ultimately we do have an ABN on file and can bill the pt as it was a voluntary signing of the ABN by the pt...:confused:
Last edited:


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Attached is MLN Matters MM6563. Explains the modifiers and their usage pretty well; however, it doesn't include payment info.

Hope it helps


  • CMS Modifier GA GX.pdf
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