K4 HCPCS Level II modifier: Lower extremity prosthesis functional level 4 - has the ability or potential for prosthetic ambulation that exceeds the basic ambulation skills, exhibiting…

K4 is a HCPCS Level II modifier: “Lower extremity prosthesis functional level 4 - has the ability or potential for prosthetic ambulation that exceeds the basic ambulation skills, exhibiting high impact, stress, or energy levels….” It adds this detail to the code it is reported with.

Official description

K4

Lower extremity prosthesis functional level 4 - has the ability or potential for prosthetic ambulation that exceeds the basic ambulation skills, exhibiting high impact, stress, or energy levels, typical of the prosthetic demands of the child, active adult, or athlete.

Short description: Lwr ext prost functnl lvl 4

HCPCS · United States

Medicare details

The indicators CMS publishes with K4 in its October 2026 file. They describe Medicare’s handling, not another payer’s.

Medicare coverage: Carrier judgment
Added: Jan 1, 1993

Where K4 sits

1GroupHCPCS modifiers
2Modifier K4Lower extremity prosthesis functional level 4 - has the ability or potential for prosthetic ambulation that exceeds the basic ambulation skills, exhibiting high impact, stress, or energy levels, typical of the prosthetic demands of the child, active adult, or athlete.

Source and release

Data release: HCPCS Level II · October 2026
Effective date: Oct 1, 2026
Publisher: CMS

This page is built from the HCPCS Level II catalog that Vero Codes reads when it suggests codes: Centers for Medicare & Medicaid Services’s October 2026 release, imported from the publisher’s file and checked against it. The description, notes and structured data come from the same record.

See K4 in the CMS source

Frequently asked questions

What does HCPCS code K4 mean?

K4 is the HCPCS code for “Lower extremity prosthesis functional level 4 - has the ability or potential for prosthetic ambulation that exceeds the basic ambulation skills, exhibiting high impact, stress, or energy levels, typical of the prosthetic demands of the child, active adult, or athlete.” in CMS’s HCPCS Level II October 2026 release.

Where is K4 in the HCPCS Level II list?

K4 is listed under Modifiers.

Does Medicare cover K4?

CMS lists K4’s Medicare coverage as “Carrier judgment”. Coverage and payment still depend on the patient, the setting, the documentation and the payer.

Which HCPCS Level II release does this page use?

It uses CMS’s October 2026 release, in effect from Oct 1, 2026 to Dec 31, 2026. It is a reference: confirm the code against the current list and the payer’s rules before you submit it.

All modifiers

JWDrug amount discarded/not administered to any patient JZZero drug amount discarded/not administered to any patient K0Lower extremity prosthesis functional level 0 - does not have the ability or potential to ambulate or transfer safely with or without assistance and a prosthesis does not enhance…K1Lower extremity prosthesis functional level 1 - has the ability or potential to use a prosthesis for transfers or ambulation on level surfaces at fixed cadence. typical of the…K2Lower extremity prosthesis functional level 2 - has the ability or potential for ambulation with the ability to traverse low level environmental barriers such as curbs, stairs or…K3Lower extremity prosthesis functional level 3 - has the ability or potential for ambulation with variable cadence. typical of the community ambulator who has the ability to…KAAdd on option/accessory for wheelchair KBBeneficiary requested upgrade for abn, more than 4 modifiers identified on claim KCReplacement of special power wheelchair interface KDDrug or biological infused through dme KEBid under round one of the dmepos competitive bidding program for use with non-competitive bid base equipment KFItem designated by fda as class iii device