HCPCS Level II modifier
Modifier AU
Modifier AU is a HCPCS Level II modifier. CMS describes it as: Item furnished in conjunction with a urological, ostomy, or tracheostomy supply.
Source: CMS HCPCS Level II, October 2026 file dated September 23, 2026. Publisher page
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- Modifier
- AU
- Type
- HCPCS Level II modifier, maintained by CMS
- CMS description
- Item furnished in conjunction with a urological, ostomy, or tracheostomy supply
- 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
- AVItem furnished in conjunction with a prosthetic device, prosthetic or orthotic
- ATAcute treatment (this modifier should be used when reporting service 98940, 98941, 98942)
- AWItem furnished in conjunction with a surgical dressing
- ASPhysician assistant, nurse practitioner, or clinical nurse specialist services for assistant at surgery
- AXItem furnished in conjunction with dialysis services
- ARPhysician provider services in a physician scarcity area
- AYItem or service furnished to an ESRD patient that is not for the treatment of ESRD
- AQPhysician providing a service in an unlisted health professional shortage area (HPSA)
Related pages
Questions
What does modifier AU mean?
Modifier AU is a HCPCS Level II modifier. CMS describes it as: Item furnished in conjunction with a urological, ostomy, or tracheostomy supply.
Is modifier AU a CPT or a HCPCS modifier?
AU 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 AU 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.