CMS ZIP-to-locality crosswalk: October 2023 release
The official CMS data behind Q4 2023 on this site — in effect October 1 – December 31, 2023. The quarterly crosswalk mapping every 5-digit ZIP code to the Medicare payment locality whose GPCIs price claims from that ZIP.
Get the file from CMS Copy link
Direct download: 2023-end-year-zip-code-file.zip
SHA-256 of the file we ingested: 8c131f2bd7460aaedd641a73349cf72b0fa24bbf591d1c288bbc07899f809ac5
Direct CMS links rot when cms.gov reorganizes — the stable fallback is the official CMS ZIP-to-locality crosswalk page.
Files inside this release Copy link
The member files we parsed, exactly as recorded at ingest — row counts and checksums let anyone verify our copy against CMS's. Where the name is a link, it downloads the exact bytes we parsed, straight out of the CMS zip — except the relative value file, marked scrubbed below, where we remove the AMA-copyrighted DESCRIPTION column before publishing and leave everything else untouched.
| File | What it is | Rows |
|---|---|---|
|
ZIP5_DEC2023_FINAL.txt
3.4 MB
SHA-256 bad6d6bf5fb5…
|
ZIP5 — the ZIP-to-locality crosswalk | 42,968 |
What the columns mean Copy link
CMS ships these files with minimal documentation, and both the column names and their order drift between releases — which is why we parse by header name, never by position. Any column position shown here is the one we recorded when parsing this release.
ZIP5 — the ZIP-to-locality crosswalk
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One row per 5-digit ZIP code, mapping it to the MAC and payment locality whose GPCIs price claims from that ZIP. This is the file that turns "what does Medicare pay here?" into a specific locality's rates.
Open ZIP5_DEC2023_FINAL.txt (3.4 MB)| Column | What it means |
|---|---|
| State | Two-letter state or territory. |
| ZIP code | The 5-digit ZIP being mapped. |
| Carrier | The MAC that processes claims for this ZIP. |
| Locality | The payment locality code the ZIP prices under. |
| Rural indicator | Blank for urban, R for rural, B for super-rural — used by the ambulance fee schedule's rural bonuses. |
| Plus-4 flag | 1 when the ZIP spans more than one locality, meaning the full ZIP+4 is needed to price precisely. |
What this release backs on this site Copy link
This crosswalk powers the ZIP-code lookups on our locality pages and the per-ZIP estimates on code pages. Ingested Aug 8, 2026. See the full pipeline in our methodology.