HL7 GP1 Segment: Grouping/Reimbursement – Visit | Vorro Academy

The GP1 segment carries visit-level grouping and reimbursement data used in DRG-based institutional billing under the Outpatient Prospective Payment System. It conveys the type of bill, the revenue codes that apply across the visit, the overall claim disposition, the outpatient code editor (OCE) edits at the visit level, and the outlier cost. GP1 summarizes a visit while its companion GP2 segment carries the per-procedure line-item detail; both relate to the DRG segment that conveys the diagnosis-related group assignment.

Purpose

GP1 provides the visit-level grouping and reimbursement context that a payer or grouper applies to an institutional claim. It identifies the type of bill, lists the revenue codes present on the visit, reports the overall disposition of the claim after editing, records the OCE edits raised at the visit level, and states the outlier cost. GP1 works alongside GP2 line items and the DRG assignment to describe how a visit is grouped and reimbursed.

Used in

UB1 (UB-82 form data) and UB2 (UB-92 form data) carry institutional-billing form information, while GP1 and GP2 carry grouping and reimbursement (DRG-based) data. GP1 appears in BAR (billing and account) messages and in ADT institutional-billing contexts, typically following the PID, PV1, and DRG segments that establish patient, visit, and grouping context.

Field-by-field reference

Source: HAPI HL7v2 v2.5.1 javadocs (GP1.html). Length is shown as —; Required and Table # are taken from the HL7 v2.5.1 standard where well-established.

Seq	Name	Data Type	Length	Req	Repeat	Table #	Description
GP1-1	Type of Bill Code	is	—	O	—	HL70455	Type of bill for the visit
GP1-2	Revenue Code	is	—	O	Y	HL70456	Revenue codes present on the visit
GP1-3	Overall Claim Disposition Code	is	—	O	—	HL70457	Disposition of the claim after editing
GP1-4	OCE Edits per Visit Code	is	—	O	Y	HL70458	Outpatient code editor edits per visit
GP1-5	Outlier Cost	cp	—	O	—	—	Outlier cost amount for the visit

Most-used fields

GP1-1 Type of Bill Code: identifies the type of bill for the visit; drives downstream payer routing.
GP1-2 Revenue Code: repeating revenue codes that summarize the chargeable categories on the visit.
GP1-3 Overall Claim Disposition Code: reports whether the claim passed editing or requires action.
GP1-4 OCE Edits per Visit Code: repeating outpatient code editor edits raised at the visit level.
GP1-5 Outlier Cost: composite price reporting the outlier cost computed for the visit.

Version differences (2.3 to 2.8.2)

GP1 was introduced with the Outpatient Prospective Payment System grouping and reimbursement work and is present in v2.4 onward; it is not part of the earliest 2.3 message structures.
Through v2.5.1 GP1 retains its five-field structure with repeating revenue codes (GP1-2) and OCE edits (GP1-4).
Composite-price refinements to the Outlier Cost field (GP1-5) across the 2.4 to 2.8.2 range tightened component definitions without changing field order.
GP1 is paired with GP2 for line-item detail throughout the 2.x range; confirm both segments' availability against the specific version in use.

Common mistakes

Confusing GP1 (visit level) with GP2 (procedure line item). GP1 summarizes the visit; GP2 details each procedure.
Collapsing repeating fields. GP1-2 Revenue Code and GP1-4 OCE Edits per Visit Code both repeat; flattening them loses detail.
Treating GP1-1 as required. All GP1 fields are optional in the standard.
Sending the outlier cost as a plain number. GP1-5 is a CP composite price and should preserve its price and currency components.
Omitting the related DRG context. GP1 grouping data is most useful alongside the diagnosis-related group assignment.

Examples

Minimal GP1 (type of bill and disposition only):

GP1|131||03

Fully populated GP1:

GP1|131|0450~0636|03|E1~E2|1850.00^USD

Annotated breakdown:

GP1|131|0450~0636|03|E1~E2|1850.00^USD
    |   |         |  |     |
    |   |         |  |     +-> GP1-5 Outlier Cost = 1850.00 USD (CP)
    |   |         |  +-------> GP1-4 OCE Edits per Visit = E1, E2 (repeating)
    |   |         +----------> GP1-3 Overall Claim Disposition Code = 03
    |   +--------------------> GP1-2 Revenue Code = 0450, 0636 (repeating)
    +------------------------> GP1-1 Type of Bill Code = 131

In-context excerpt inside a BAR^P01 (billing account) message, after PID, PV1, and DRG:

MSH|^~&|REGISTRATION|MERCYGEN|BILLING|MERCYGEN|20260610113000||BAR^P01^BAR_P01|MSG10243|P|2.5.1
EVN|P01|20260610113000
PID|1||MRN884412^^^MERCYGEN^MR||DOE^JANE^Q||19710204|F
PV1|1|O|EDOP^^^MERCYGEN||||1023^WELBY^MARCUS|||EMR||||A|||1023^WELBY^MARCUS|OP|ACC778901|||||||||||||||||||||||||20260601|20260601
DRG|470^Major Joint Replacement^MS-DRG|20260601|Y
GP1|131|0450~0636|03|E1~E2|1850.00^USD

Second in-context excerpt (a shorter visit-level grouping following DRG):

MSH|^~&|REGISTRATION|RIVEROAKS|BILLING|RIVEROAKS|20260609090000||BAR^P01^BAR_P01|MSG55014|P|2.5.1
EVN|P01|20260609090000
PID|1||MRN200337^^^RIVEROAKS^MR||SMITH^ROBERT^A||19640812|M
PV1|1|O|CLINIC^^^RIVEROAKS||||2210^HOUSE^GREGORY|||OUT||||A|||2210^HOUSE^GREGORY|OP|ACC661204|||||||||||||||||||||||||20260520|20260520
DRG|313^Chest Pain^MS-DRG|20260520|N
GP1|131|0510|01||

FHIR mapping

Source: GP1.
Target: Not mapped at the segment level.
Notes: No segment-level ConceptMap is published in the v2-to-FHIR IG for GP1. Institutional-billing data maps conceptually to the FHIR Claim resource (UB-04/837I billing). Type of bill, revenue codes, claim disposition, and outlier cost align with Claim.type, Claim.item, and Claim.adjudication rather than a single normalized field.

Engine considerations

GP1 fields are optional; a conformant engine should accept a sparsely populated GP1.
Preserve repetitions in GP1-2 Revenue Code and GP1-4 OCE Edits per Visit Code using repetition-aware accessors.
Validate the Outlier Cost (GP1-5) as a CP composite, retaining price and currency components.
Treat GP1 as visit-level context that complements GP2 line items and the DRG assignment; keep the three associated when routing.
Apply the established tables (HL70455 type of bill, HL70456 revenue code, HL70457 disposition, HL70458 OCE edits) for validation where configured.

How Vorro parses and produces GP1

Vorro parses GP1 into a normalized visit-level grouping model that keeps the repeating revenue codes (GP1-2) and OCE edits (GP1-4) as lists and reads the outlier cost (GP1-5) as a typed composite price with its currency component. When producing GP1, Vorro emits fields in standard sequence, populates only the elements present in the source claim, and preserves the coded values against the established type-of-bill, revenue, disposition, and OCE-edit tables. GP1 is kept associated with its companion GP2 line items and the related DRG assignment so the visit's grouping and reimbursement picture stays intact end to end.

Sources

← Back to HL7 v2 Guide

HL7 GP1 Segment: Grouping/Reimbursement – Visit