AJ Modifier Description: Clinical Social Worker
If your practice employs LCSWs, you have probably seen AJ on a payer's billing guide. Whether you need it depends entirely on who is paying, because several state Medicaid programs identify social workers with different modifiers.
Short answer
AJ is the HCPCS Level II modifier "Clinical social worker." It identifies a service by a clinical social worker, and some plans, such as Anthem, list it among modifiers that can affect reimbursement. State Medicaid programs vary: Michigan bills master's-level social workers with HO and bachelor's with HN, and Ohio uses U4 for licensed social workers, U8 for social work assistants, and U9 for trainees.
| Modifier | HCPCS descriptor | Type |
|---|---|---|
| AJ | Clinical social worker | Provider discipline |
Where AJ applies
AJ is an informational discipline modifier. Payers that use it list it in their modifier or reimbursement policies; Anthem's reimbursement modifier list includes AJ alongside AH, HN, HO, and HP. There is no single national rule requiring it on every social work claim, so the payer's own guide is the source of truth.
States that identify social workers differently
| State program | Social worker | Modifier |
|---|---|---|
| Michigan PIHP encounters | Licensed or limited licensed social worker, master's | HO |
| Michigan PIHP encounters | Licensed or limited licensed social worker, bachelor's | HN |
| Ohio Medicaid | Licensed social worker (LSW) | U4 |
| Ohio Medicaid | Social worker assistant | U8 |
| Ohio Medicaid | Social worker trainee | U9 |
Texas pays LCSWs, LMFTs, and LPCs 70 percent of the rate paid to a psychiatrist or psychologist for a similar service, and only the LCSW actually performing the service may bill it, not services by people under their supervision.
Why AJ claims deny
- Payer does not use AJ. The claim carries AJ where the state expects HO, U4, or another modifier.
- Payer requires AJ and it is missing. The plan's policy requires the discipline modifier on social work services.
- AJ and AH swapped. AJ is clinical social worker; AH is clinical psychologist.
Related: AH, HO, all behavioral health HCPCS modifiers, and the code map in H codes in behavioral health.
Sources, read October 2026: Anthem modifier usage code list; MDHHS SFY 2027 Behavioral Health Code Charts and Provider Qualifications; Ohio Medicaid Behavioral Health Provider Manual, v1.28.1 (March 2026); Texas Medicaid Behavioral Health and Case Management Services Handbook (January 2026). Federal HCPCS descriptors are CMS public data. State manuals and plan contracts change; confirm the current edition before billing.
Frequently asked questions
What is the AJ modifier description?
AJ is the HCPCS Level II modifier "Clinical social worker." It identifies a service rendered by a clinical social worker.
Is the AJ modifier required for LCSW claims?
Only where the payer requires it. Some plans list AJ in their reimbursement policies; several state Medicaid programs use other modifiers for social workers, such as HO in Michigan or U4 in Ohio.
What is the AJ modifier for behavioral health?
It identifies the clinical social worker discipline on behavioral health services, mainly for payers whose policies call for it.
Social work claims, matched to each payer.
See Stable apply AJ, HO, or the state's own modifier based on who is paying.
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