The KY modifier in Medicare is a DMEPOS competitive bidding modifier. It flags claims for certain competitively bid wheelchair accessories when those accessories are used with specific non-competitively bid power wheelchair base units furnished to beneficiaries who live in a competitive bidding area.1Noridian Medicare. Modifier KY It is not a physician services modifier, and it has nothing to do with Health Professional Shortage Area (HPSA) bonus payments, even though it is often confused with the modifier that does trigger that bonus.
What the KY Modifier Signals on a Claim
KY lives entirely inside Medicare’s durable medical equipment, prosthetics, orthotics, and supplies (DMEPOS) world. The specific situation it marks is narrow: a wheelchair accessory that falls under the competitive bidding program, attached to a power wheelchair base unit that does not fall under competitive bidding, for a beneficiary whose address places them inside a competitive bidding area.1Noridian Medicare. Modifier KY
If any of those pieces is missing — the accessory is not competitively bid, the base is itself a competitively bid item, or the beneficiary does not live in a competitive bidding area — KY is not the right modifier for the line.
Where KY Does Not Belong
Two misuses show up often enough to call out directly.
The first is appending KY to a professional services claim. KY has no function on a Physician Fee Schedule claim. It will not change payment, and it does not identify the service for any incentive program.
The second is using KY to try to claim Medicare’s 10% HPSA physician bonus. That bonus has its own modifier, and KY is not it. A claim submitted with KY in hopes of triggering a shortage-area bonus will simply not receive one.
The Modifier People Often Mean Instead: AQ
Searchers land on “KY modifier” when they are actually looking for AQ, the modifier tied to the HPSA physician bonus. The HPSA bonus pays an additional 10% on top of the Medicare-paid amount for professional services furnished in qualifying shortage areas, and AQ is the code that identifies those services when identification is needed.2eCFR. 42 CFR 414.67 – Incentive Payments for Services Furnished in Health Professional Shortage Areas
Who Can Receive the Bonus
Eligibility is limited to two groups:
- Physicians (doctors of medicine and osteopathy, under Medicare’s statutory definition) who furnish Medicare-covered professional services in a geographic primary care HPSA.
- Psychiatrists who furnish Medicare-covered services in a geographic mental health HPSA, where that area is not also designated as a primary care HPSA.
CMS guidance does not extend the bonus to non-physician practitioners such as physician assistants or nurse practitioners.3Centers for Medicare & Medicaid Services. Physician Bonuses in Health Professional Shortage Areas (HPSAs) Only geographic HPSA designations qualify. Population-group and facility-based designations recognized by HRSA for other federal programs do not trigger the Medicare bonus.4eCFR. 42 CFR Part 5 – Designation of Health Professional(s) Shortage Areas
When an area carries both a geographic primary care and a geographic mental health HPSA designation, the primary care designation controls for all eligible physicians, psychiatrists included. The mental health designation only matters where there is no primary care designation covering the same area.5Centers for Medicare & Medicaid Services (CMS). Health Professional Shortage Area Physician Bonus Program
Physicians providing inpatient or outpatient care in a Critical Access Hospital located within a geographic HPSA can also qualify. Where a surgeon has reassigned benefits to a CAH paid under the optional method, the bonus goes to the CAH on an institutional claim rather than to the surgeon directly.2eCFR. 42 CFR 414.67 – Incentive Payments for Services Furnished in Health Professional Shortage Areas
When AQ Is Required and When It Is Not
Many HPSA bonus payments process automatically, without any modifier. CMS publishes separate annual primary care and mental health HPSA ZIP code lists, and services provided in a ZIP code on the current year’s automated list are identified by Medicare without provider action.3Centers for Medicare & Medicaid Services. Physician Bonuses in Health Professional Shortage Areas (HPSAs) The ZIP code qualifies for automatic payment in three situations:
- The ZIP code falls entirely within a county designated as a full-county HPSA.
- The ZIP code falls partially within a full-county HPSA but is treated as being in that county under a USPS dominance determination.
- The ZIP code falls entirely within a partial-county HPSA designation.
You need to append AQ when the service location sits in a geographic HPSA but its ZIP code is not on the automated list. This typically happens with split ZIP codes that are not USPS-dominant in a full-county HPSA, ZIP codes that straddle the boundary of a partial-county HPSA, and areas designated after the data run used to build the annual file. Without AQ on these claims, Medicare has no way to identify them for the bonus, and the 10% will not be paid.2eCFR. 42 CFR 414.67 – Incentive Payments for Services Furnished in Health Professional Shortage Areas
Verifying Eligibility Before You Append AQ
Confirm the service address actually sits in a qualifying geographic HPSA before using AQ. Medicare may review claims carrying the modifier to validate the location, and an incorrect use can draw post-payment review.3Centers for Medicare & Medicaid Services. Physician Bonuses in Health Professional Shortage Areas (HPSAs)
Check the current year’s CMS primary care and mental health HPSA ZIP code lists first. If your ZIP code is on either list, the payment is automatic and no modifier is needed. If it is not, run the street address through HRSA’s Medicare Physician Bonus Payment Eligibility Analyzer,6HRSA Data Warehouse. Medicare Physician Bonus Payment Eligibility Analyzer and cross-reference HRSA’s HPSA Find tool to confirm the designation type is geographic rather than population-group or facility-based.7HRSA Data Warehouse. HPSA Find Include the name, address, and ZIP code of the actual service location on the claim; for addresses not on the automated file, Medicare matches at the street level.
Quick Reference
KY: DMEPOS claims only, for certain competitively bid wheelchair accessories used with non-competitively bid power wheelchair bases in competitive bidding areas.
AQ: Professional services claims only, for physicians (and psychiatrists in mental health HPSAs) furnishing services in a geographic HPSA whose ZIP code is not on the current automated HPSA file.
If you were searching “KY modifier” because you expected a Medicare bonus payment to follow, AQ is the modifier you want, and only on claims where the automated file does not already handle the identification.