getreadystack/hmrc-fraud-prevention-header-lint repository overview

⁠HMRC Fraud Prevention Header Lint for Making Tax Digital (VAT and Income Tax)

Finds the Gov-Client and Gov-Vendor header mistakes HMRC rejects, in your editor, offline, before you send the request.

⁠Run

docker run --rm -v "$PWD":/work getreadystack/hmrc-fraud-prevention-header-lint /work/file

The same 34 rules as the VS Code extension, in a container. Mount a folder on /work.

⁠Free

• Check the file you have open, or just the lines you select, against all 34 HMRC fraud prevention header rules, offline, and get the exact spelling HMRC accepts for every problem found.
• --rules lists every rule

⁠With a licence ($29 once)

• Scans every file in the workspace, exports a CSV, JSON or HTML report, prints machine-readable output so CI can fail the build, and auto-corrects the header names that have exactly one correct spelling.

docker run --rm -e READYSTACK_LICENSE=<key> -v "$PWD":/work getreadystack/hmrc-fraud-prevention-header-lint --dir /work --ci

HMRC charges a 200 pound penalty once a filer crosses the points threshold for late MTD quarterly updates, and HMRC's own header validator only grades a live request you have already sent.

⁠Use from an AI agent (MCP)

Claude Code · Cursor · Windsurf · any MCP client - add to your MCP config:

{ "mcpServers": { "hmrc-fraud-prevention-header-lint": { "command": "npx", "args": ["-y", "@readystack/hmrc-fraud-prevention-header-lint", "--mcp"] } } }

Tools: check_text and check_file (free) · check_dir (licence; the full sweep is free for 7 days). The agent gets every finding with the line number.

⁠Use in CI

- name: HMRC Fraud Prevention Header Lint for Making Tax Digital (VAT and Income Tax)
  run: npx -y @readystack/hmrc-fraud-prevention-header-lint --dir . --ci

(container: docker run --rm -v "$PWD:/work" getreadystack/hmrc-fraud-prevention-header-lint --dir /work --ci)

Try the full run free for 7 days — no key needed. Then one licence, 7-day refund, no questions. Set READYSTACK_LICENSE=<key> or run --license <key> once.

Get a licence⁠