Modifier K1

Lower extremity prosthesis functional level 1 - The beneficiary has the ability or potential to use a prosthesis for transfers or ambulation on level surfaces at fixed cadence. Typical of the limited and unlimited household ambulator.

Certain components/additions to the prosthesis are based on the beneficiary's potential functional abilities based on reasonable expectations of the prosthetist and treating physician considering factors including but not limited to; beneficiary's past history (including prior prosthetic use if applicable), and beneficiary's current condition including status of residual limb and nature of other medical problems, and beneficiary's desire to ambulate. The supplier then bills a modifier on the claim to indicate the beneficiary's potential functional level (K0 to K4).

Although the specific modifier (K0-K4) is not required in either the prosthetist's or physician's notes, the records must clearly document the beneficiary's functional level to support the use of that particular functional level modifier.

Denial Reasons

Although these aren't all the top reasons for denial, there is a common theme amongst claim denials for both the L5980 and L5981.

  • Documentation did not support the functional level billed on the claim,
  • documentation did not support the beneficiary's functional maintenance or their motivated ambulation and
  • incomplete billing documentation for functional level was provided.

Note: In order to satisfy requirement, functional level must be documented by both prosthetist and ordering physician



Last Updated Sep 27 , 2022