HCPCS Level II modifier
Modifier KO
Modifier KO is a HCPCS Level II modifier. CMS describes it as: Single drug unit dose formulation.
Source: CMS HCPCS Level II, October 2026 file dated September 23, 2026. Publisher page
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- Modifier
- KO
- Type
- HCPCS Level II modifier, maintained by CMS
- CMS description
- Single drug unit dose formulation
- Claim form
- CMS-1500 item 24D, up to four modifiers per line. 837P SV101-3 to SV101-6.
- Guidance
- CMS HCPCS quarterly update
Related modifiers
- KPFirst drug of a multiple drug unit dose formulation
- KNReplacement of facial prosthesis using previous master model
- KQSecond or subsequent drug of a multiple drug unit dose formulation
- KMReplacement of facial prosthesis including new impression/moulage
- KRRental item, billing for partial month
- KLDMEPOS item delivered via mail
- KSGlucose monitor supply for diabetic beneficiary not treated with insulin
- KKDMEPOS item subject to DMEPOS competitive bidding program number 2
Related pages
Questions
What does modifier KO mean?
Modifier KO is a HCPCS Level II modifier. CMS describes it as: Single drug unit dose formulation.
Is modifier KO a CPT or a HCPCS modifier?
KO is a HCPCS Level II modifier from the CMS quarterly HCPCS file. Two-digit numeric modifiers, such as 25 or 59, are CPT modifiers.
Where does modifier KO go on a claim?
On the CMS-1500 it goes in item 24D next to the procedure code. Each line holds up to four modifiers. On an 837P it goes in SV101-3 to SV101-6.
What denial comes back when a modifier is wrong?
A missing or mismatched modifier often comes back as CARC 4. A modifier that was not valid on the date of service comes back as CARC 182. A bundling edit the modifier should have bypassed comes back as CARC 97 or 236.