Look up federal per diem rates by ZIP code.

Accepts 5-digit ZIPs or ZIP+4 (e.g., '02101' or '02101-1234'). Bundled fiscal years are answered from GSA's published ZIP file with no API call; other years use the GSA Per Diem API.

GSA sets rates by county or locality, and about 1,800 ZIPs span more than one rate area. The result's status is 'resolved' when every rate area GSA lists for the ZIP has the same rate, otherwise 'ambiguous' with all candidates and no single rate chosen. county (optional) selects the candidate for that county.