Modifier AU
Modifier AU Description and Billing Use
Plain-language description
Supply relationship modifier where applicable.
How modifier AU is used
AU identifies an item furnished in conjunction with a urological, ostomy, or tracheostomy supply. Its use is code- and policy-specific: for example, the reviewed Medicare urological policy requires AU on A4217, A4450, and A4452 when used with urological supplies. Do not append AU broadly to every related supply.
Modifier AU questions
What does the AU modifier mean?
AU identifies an item furnished in conjunction with a urological, ostomy, or tracheostomy supply when the applicable Medicare policy requires that relationship modifier.
Which codes use AU for Medicare urological supplies?
The reviewed urological policy article requires AU on A4217, A4450, and A4452 when those codes are used with urological supplies.
Can AU be added to every urological, ostomy, or tracheostomy claim?
No. AU is code- and policy-specific. Verify the HCPCS code, benefit relationship, and current policy before reporting it.
Before reporting this modifier
- 1. Confirm the current official or licensed definition and payer acceptance.
- 2. Identify the exact claim circumstance the modifier communicates.
- 3. Make the code, setting, related services, and medical record consistent.
- 4. Check NCCI, global surgery, component, DME, ABN, or drug rules that apply.
- 5. Do not append a modifier only to force an edit override.
This is a workflow summary, not a licensed CPT definition or claim-specific coding instruction. Verify the code set and payer rule effective for the date of service.