The AUT (Authorization Information) segment carries the payer-side authorization detail that accompanies a referral, an order, or another clinical or financial transaction that needs prior approval. It identifies which payor and plan authorized the service, the unique authorization number, the dates the authorization is effective, any reimbursement limit, and the requested versus authorized number of treatments.
AUT is most often seen attached to a referral provider or to an insurance block. It binds a clinical request to the financial pre-approval that lets the service be performed and billed, and it is the segment that downstream systems read to confirm that an inbound order has been cleared by the payer.
Used in
AUT carries authorization detail in referral and order messages — see REF message. It appears in the patient referral message (REF^I12 and related triggers) inside the financial / payment group alongside IN1 insurance and PRD provider data, and in order messages that need a captured authorization on the request.
Field-by-field reference
The table below lists every field defined for AUT in HL7 v2.5.1 as exposed by the HAPI structure. The Seq column is the field identifier (AUT-1 through AUT-10), Req reflects HL7's optionality (R only where the standard requires the field), Repeat indicates whether the field is defined as repeating in the segment structure, and Table # references the HL7-defined value set when one is well established.
| Seq | Name | Data Type | Length | Req | Repeat | Table # | Description |
|---|---|---|---|---|---|---|---|
| AUT-1 | Authorizing Payor, Plan ID | ce | — | O | — | [HL70072] | Coded plan under which service is authorized |
| AUT-2 | Authorizing Payor, Company ID | ce | — | R | — | [HL70285] | Coded payor company granting the authorization |
| AUT-3 | Authorizing Payor, Company Name | st | — | O | — | — | Printable name of the authorizing payor |
| AUT-4 | Authorization Effective Date | ts | — | O | — | — | Date the authorization becomes effective |
| AUT-5 | Authorization Expiration Date | ts | — | O | — | — | Date the authorization expires |
| AUT-6 | Authorization Identifier | ei | — | O | — | — | Unique authorization or pre-cert number |
| AUT-7 | Reimbursement Limit | cp | — | O | — | — | Maximum amount the payor will reimburse |
| AUT-8 | Requested Number of Treatments | nm | — | O | — | — | Number of treatments requested by provider |
| AUT-9 | Authorized Number of Treatments | nm | — | O | — | — | Number of treatments approved by payor |
| AUT-10 | Process Date | ts | — | O | — | — | Date the authorization was processed |
Examples
Minimal AUT
AUT|||AETNA HMO||||AUTH-2026-554120
Fully-populated AUT
AUT|HMO^HMO Plan^HL70072|60054^AETNA^HL70285|AETNA HMO|20260601000000|20260901000000|AUTH-2026-554120^AETNA^2.16.840.1.113883.19.4.5^ISO|2500.00^USD|12|10|20260530143000
Annotated breakdown
AUT|HMO^HMO Plan^HL70072|60054^AETNA^HL70285|AETNA HMO|20260601000000|20260901000000|AUTH-2026-554120^AETNA^2.16.840.1.113883.19.4.5^ISO|2500.00^USD|12|10|20260530143000
| | | | | | | | | |
| | | | | | | | | +-- AUT-10 Process Date
| | | | | | | | +----- AUT-9 Authorized Number of Treatments = 10
| | | | | | | +-------- AUT-8 Requested Number of Treatments = 12
| | | | | | +----------------------- AUT-7 Reimbursement Limit = 2500.00 USD
| | | | | +----------------------------------------------------------------------------------- AUT-6 Authorization Identifier
| | | | +------------------------------------------------------------------------------------------------------ AUT-5 Authorization Expiration Date
| | | +---------------------------------------------------------------------------------------------------------------------- AUT-4 Authorization Effective Date
| | +--------------------------------------------------------------------------------------------------------------------------------- AUT-3 Authorizing Payor, Company Name
| +-------------------------------------------------------------------------------------------------------------------------------------------------------- AUT-2 Authorizing Payor, Company ID
+---------------------------------------------------------------------------------------------------------------------------------------------------------------------------- AUT-1 Authorizing Payor, Plan ID
In-context excerpts
AUT inside a REF^I12 patient referral
MSH|^~&|EHR|CLINIC_A|REFMGR|SPECIALTY_GRP|20260610091500||REF^I12^REF_I12|MSG00101|P|2.5.1
RF1|A|R|I|REF-2026-00077|RXR-2026-00077|20260610091500|||
PRD|RP|JONES^ALAN^MD^^^DR|123 PRIMARY WAY^^SPRINGFIELD^IL^62701|||(217)555-0117|||^^^NPI^^^1730254421
PRD|RT|CHEN^MEI^MD^^^DR|400 SPECIALTY DR^^SPRINGFIELD^IL^62702|||(217)555-0250|||^^^NPI^^^1417885320
PID|1||7741882^^^MRN||DOE^JANE^A||19720815|F|||742 EVERGREEN TER^^SPRINGFIELD^IL^62704
IN1|1|HMO^HMO Plan^HL70072|60054^AETNA^HL70285|AETNA HMO|PO BOX 14463^^LEXINGTON^KY^40512||||GRP-998||||20260101|||DOE^JANE^A|SLF|19720815|742 EVERGREEN TER^^SPRINGFIELD^IL^62704
AUT|HMO^HMO Plan^HL70072|60054^AETNA^HL70285|AETNA HMO|20260601000000|20260901000000|AUTH-2026-554120^AETNA^2.16.840.1.113883.19.4.5^ISO|2500.00^USD|12|10|20260530143000
AUT on an order requiring prior authorization
MSH|^~&|EHR|CLINIC_A|RIS|IMAGING_CTR|20260610104000||OMI^O23^OMI_O23|MSG00102|P|2.5.1
PID|1||7741882^^^MRN||DOE^JANE^A||19720815|F|||742 EVERGREEN TER^^SPRINGFIELD^IL^62704
IN1|1|PPO^PPO Plan^HL70072|71045^BCBS_IL^HL70285|BCBS OF ILLINOIS|300 RANDOLPH^^CHICAGO^IL^60601||||GRP-44210||||20260101|||DOE^JANE^A|SLF|19720815|742 EVERGREEN TER^^SPRINGFIELD^IL^62704
AUT|PPO^PPO Plan^HL70072|71045^BCBS_IL^HL70285|BCBS OF ILLINOIS|20260610000000|20260710000000|AUTH-IMG-2026-00318^BCBS^2.16.840.1.113883.19.4.6^ISO|900.00^USD|1|1|20260609160000
ORC|NW|ORD-2026-44119||GRP-2026-7741|||^^^20260612080000|||||1730254421^JONES^ALAN^MD
OBR|1|ORD-2026-44119||72148^MRI LUMBAR SPINE WO CONTRAST^CPT|||20260612080000
Implementation notes
- AUT-2 (Authorizing Payor, Company ID) is the only field the standard marks as required; receivers should reject or query messages that omit it because there is no way to attribute the authorization without the payor.
- AUT-6 (Authorization Identifier) is the operational handle that downstream billing and scheduling systems use to look up the authorization. Even though the standard marks it optional, real-world trading partners almost always require it.
- AUT-4 and AUT-5 bracket the validity window. Receivers should not honor an authorization outside that window even if the identifier matches.
- AUT-8 and AUT-9 together let a payor return fewer treatments than requested (for example, requested 12, authorized 10), so applications should compare them and surface partial approvals to schedulers.
- AUT-7 (Reimbursement Limit) carries both amount and currency via the CP data type; never assume USD.
- In v2.5.1, the financial / payment group around AUT does not include PYE (payee) or DPR (practitioner distribution) at the segment level for the REF flows commonly used in practice, so this page does not describe them.
FHIR mapping
The HL7 v2-to-FHIR Implementation Guide does not publish a segment-level ConceptMap for AUT. In practice, AUT data is split across FHIR Coverage (payor and plan identifiers) and a referral-style authorization resource — for example CoverageEligibilityResponse, Claim pre-authorization, or ServiceRequest.insurance — with AUT-6 surfacing as the authorization identifier and AUT-4 / AUT-5 as the authorization period.
