HCPCS Level II modifier
Modifier AS
Modifier AS is a HCPCS Level II modifier. CMS describes it as: Physician assistant, nurse practitioner, or clinical nurse specialist services for assistant at surgery.
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
- AS
- Type
- HCPCS Level II modifier, maintained by CMS
- CMS description
- Physician assistant, nurse practitioner, or clinical nurse specialist services for assistant at surgery
- Claim form
- CMS-1500 item 24D, up to four modifiers per line. 837P SV101-3 to SV101-6.
- Guidance
- CMS HCPCS quarterly update
More than one surgeon
Related modifiers
- 62Two surgeons
- 66Surgical team
- 80Assistant surgeon
- 81Minimum assistant surgeon
- 82Assistant surgeon when no qualified resident was available
- ATAcute treatment (this modifier should be used when reporting service 98940, 98941, 98942)
- ARPhysician provider services in a physician scarcity area
- AUItem furnished in conjunction with a urological, ostomy, or tracheostomy supply
Related pages
- All CPT and HCPCS modifiersA to Z list
- CMS-1500 claim formModifiers go in item 24D
- Denial code CO-4Modifier missing or does not fit the code
- Denial code CO-182Modifier invalid on the date of service
- Denial code CO-97Included in another service
- Denial code CO-236Procedure or modifier pair not compatible
- HCPCS Level II code lookup
- Denial and remark codes
Questions
What does modifier AS mean?
Modifier AS is a HCPCS Level II modifier. CMS describes it as: Physician assistant, nurse practitioner, or clinical nurse specialist services for assistant at surgery.
Is modifier AS a CPT or a HCPCS modifier?
AS 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 AS 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.