Guide · Claims

How a Medicare Claim Is Built

Every payment this site models — PDPM, PDGM, hospice per-diems, therapy units — eventually lands on a claim. For post-acute facilities that claim is the UB-04. Here’s how it’s structured and where the case-mix pieces sit.

In short

Facilities bill the UB-04 (electronically, the 837I) — an institutional claim with 81 form locators that organizes charges around revenue codes. The type of bill says what kind of claim it is; the HIPPS case-mix code rides on a revenue line. Individual practitioners use the professional CMS-1500 (837P) instead.

Two kinds of claim

Medicare splits billing into two lanes. Institutional claims cover facility services — the room, nursing, and bundled care paid under systems like PDPM or PDGM. Professional claims cover an individual practitioner’s services. Post-acute providers are facilities, so they bill institutional claims.

Two claim families. Facilities bill the institutional UB-04 (electronically, the 837I); individual practitioners bill the professional CMS-1500 (the 837P). Post-acute providers live on the UB-04.

Inside the UB-04

The form’s 81 numbered fields look daunting, but they fall into a handful of blocks: who’s billing and who was treated, what kind of claim it is, the diagnoses and coded circumstances of care, the charges, and the payer. The case-mix payment lives in the charges.

The UB-04 has 81 numbered “form locators,” but they group into a few logical blocks. The case-mix payment piece — the HIPPS code — lives down in the revenue-code lines.

The type of bill

One small field does a lot of work. The type of bill tells Medicare the kind of facility, how the bill is classified, and its frequency — whether it’s a complete stay, an interim bill in a long stay, a replacement, or a void.

The type-of-bill code packs three facts into a few digits: the kind of facility, how the bill is classified, and the frequency — whether it’s a full stay, an interim bill, a replacement, or a void.

Revenue-code lines

This is what makes a UB-04 different from a professional claim: charges are organized around revenue codes (department or service categories), not just procedure lines. Each line pairs a revenue code with optional HCPCS or HIPPS, units, a date, and a charge — and the grouper’s HIPPS output sits on a specific line.

A revenue line ties a department/category code to what was provided, when, how much, and the charge. The case-mix HIPPS code sits on a specific revenue line — 0022 for SNF, 0023 for home health.

Paper and electronic

The paper UB-04 and the electronic 837I carry the same data — they’re two forms of one claim, both defined by the National Uniform Billing Committee (NUBC). Almost all claims go electronically; the paper layout still matters because rejection messages reference its form-locator numbers.

Key takeaways

Facilities bill the UB-04 / 837I; practitioners bill the CMS-1500 / 837P.
The UB-04 organizes charges around revenue codes, not just procedures.
The type of bill encodes facility type, classification, and frequency.
The HIPPS case-mix code rides a revenue line — 0022 (SNF), 0023 (home health).
Paper UB-04 and electronic 837I are the same claim; the NUBC maintains both.

Try it on the tools

Type of Bill Decoder →Revenue Codes →UB-04 Codes →Crosswalks →

Last reviewed May 2026. Educational overview only — code descriptions are paraphrased; verify against the current NUBC UB-04 manual and your MAC’s billing guidance before submitting claims.