HCPCS Level II modifier
Modifier N1
Modifier N1 is a HCPCS Level II modifier. CMS describes it as: Group 1 oxygen coverage criteria met.
Source: CMS HCPCS Level II, October 2026 file dated September 23, 2026. Publisher page
Run it in Rivvi
Check the codes on your claims export
Upload a claims export. Rivvi flags ICD-10 and HCPCS codes that are not billable or are replaced. It does not check modifiers.
Check my exportFree to start. Opens Rivvi, the AI workspace for healthcare teams.
- Modifier
- N1
- Type
- HCPCS Level II modifier, maintained by CMS
- CMS description
- Group 1 oxygen coverage criteria met
- 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
- N2Group 2 oxygen coverage criteria met
- MSSix month maintenance and servicing fee for reasonable and necessary parts and labor which are not covered under any manufacturer or supplier warranty
- N3Group 3 oxygen coverage criteria met
- MHUnknown if ordering professional consulted a clinical decision support mechanism for this service, related information was not provided to the furnishing professional or provider
- NBNebulizer system, any type, FDA-cleared for use with specific drug
- MGThe order for this service does not have applicable appropriate use criteria in the qualified clinical decision support mechanism consulted by the ordering professional
- NRNew when rented (use the 'NR' modifier when DME which was new at the time of rental is subsequently purchased)
- MFThe order for this service does not adhere to the appropriate use criteria in the clinical decision support mechanism consulted by the ordering professional
Related pages
Questions
What does modifier N1 mean?
Modifier N1 is a HCPCS Level II modifier. CMS describes it as: Group 1 oxygen coverage criteria met.
Is modifier N1 a CPT or a HCPCS modifier?
N1 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 N1 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.