MRF JSON Format Guide: How to Structure Your Machine-Readable File Correctly

Why Format Matters

CMS requires a machine-readable format — JSON or CSV that software can parse automatically. If your file doesn't parse cleanly, CMS treats the data as not published. Format errors trigger the same $5,500/day fine as missing data.

The Core JSON Structure

A compliant MRF groups data by payer, then by plan, then by item or service. Each entry includes: billing code, description, gross charge, discounted cash price, and negotiated rate. The JSON must be valid, complete, and consistent.

Required Data Fields

At minimum: item name, billing code (CPT/HCPCS), gross charge, discounted cash price, minimum and maximum negotiated rates, and per-payer negotiated rates with clear plan identifiers.

Common JSON Errors

The most frequent issues: malformed JSON (missing brackets, trailing commas), inconsistent code formats, duplicate entries, empty price fields, and files that exceed CMS size limits or time out.

Testing Your File

Before publishing, validate the JSON with a parser, verify all fields are populated, and confirm an automated crawler (not just a browser) can download it.

The Validator Advantage

A compliance validator parses your file exactly the way CMS's systems do — catching format errors, missing fields, and structural problems before they become fines.

Not sure your JSON parses cleanly? Free MRF risk check catches format errors too.

Get Your Free Risk Check