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mcp-per-diem

Work out the daily travel allowance for a business trip on the rate tables the tax authorities actually publish, and keep the trips you priced. You give it where you went, when you left and when you got back, and which meals somebody else paid for; it gives you the amount per day and the total, in the scheme's own currency, with the partial-day rule and every meal deduction shown next to the number that produced it. Three schemes ship with it: the Polish delegation regulation (domestic and per country), the HMRC benchmark scale rates for travel inside the UK, and the US GSA CONUS standard M&IE and lodging. The tables are bundled files, not a live feed, so the same trip priced twice gives the same answer, and every rate carries the regulation, the source URL and the date it took effect. Nothing leaves your machine.

Built by theluckystrike.

Install

Claude Desktop (~/Library/Application Support/Claude/claude_desktop_config.json):

{
  "mcpServers": {
    "per-diem": {
      "command": "npx",
      "args": ["-y", "@theluckystrike/mcp-per-diem"]
    }
  }
}

Claude Code:

claude mcp add per-diem -- npx -y @theluckystrike/mcp-per-diem

Cursor (~/.cursor/mcp.json or .cursor/mcp.json): the same entry as Claude Desktop.

Tools

tool what it does
perdiem_rates List a scheme's bundled rates with the authority, instrument, source URL and effective date. Filter by country or city.
perdiem_calc Price one trip: the allowance per day and the total, with the partial-day fraction and the meal deductions the scheme's rule applies.
trip_record Calculate a trip and save it under a name, with the traveller from the shared business profile.
trip_list List saved trips with a total per currency.
trip_export The exact expense_add arguments for a saved trip, one payload per currency, for the expense-tracker server.
perdiem_report Totals per scheme and per calendar month, in each scheme's own currency.
license_status Free or Pro, and where to upgrade.
license_activate Activate a Pro key. Verified offline.

Free vs Pro

Free Pro
perdiem_rates, perdiem_calc Yes, unlimited Yes
Trips saved per calendar month 5, by start date Unlimited
trip_list Yes, unlimited Yes
trip_export No Yes
perdiem_report No Yes

Get Pro — $19 one-time, or $39 for the bundle. Or the nineteen-server bundle for $39.

What is in the tables, and what is deliberately not

Every table under src/tables/ carries a header with the authority, the instrument, the source URL, the date the rates took effect and the date they were read. perdiem_rates returns that header with the rates, so the provenance travels with the number.

The rule for what is in them: a value that could not be stated with confidence from the public regulation text was left out, not guessed. A per diem figure ends up on a tax return. A wrong one that looks authoritative is worse than an absent one, because an absent one is refused by name and you go and look it up.

table bundled left out
Poland, domestic The 45.00 PLN daily diet, the 150 percent lodging lump sum, and the partial-day and meal rules The 20 percent local-transport lump sum is listed but not paid: it is not subsistence
Poland, foreign 34 countries of the annex, with the diet and its currency The other roughly 90 countries, and every per-country lodging limit. A missing country means "not verified here", not "no rate exists"
UK, domestic All four HMRC benchmark scale rates (5, 10 and 15 hour bands and the late-evening supplement) Nothing
UK, overseas Nothing. The file ships with an empty rate list and a header saying so The whole per-city overseas scale-rate table: roughly 250 cities times eight figures each, in the destination currency. This build could not state them with confidence, so none of them is bundled. perdiem_calc {scheme:"uk"} refuses a foreign destination by name and points at the HMRC page
US, GSA The CONUS standard M&IE and lodging cap for FY2025 and FY2026, with the published meal breakdown The roughly 300 non-standard localities (New York City, San Francisco and the rest). A destination that is not one of those takes the standard rate anyway, which is what this table gives

Rates change. Check the effective_date in any answer before you rely on it, and read the source_url if the trip is recent.

Rules the calculator applies

Exporting to the expense tracker

trip_export returns the exact expense_add arguments for the expense-tracker server, one payload per currency, and writes nothing itself. That is deliberate: expense-tracker publishes no library entry point, and its id counter, its category rules, its VAT split and its currency defaults all live inside its own expense_add handler under its own lock. Appending a row to its data.json directly would produce an expense with none of those applied — one that looks native and is not. Handing back the arguments is the same contract kanban uses for time-tracker's timer_start.

No vat_rate is set on the payload. A statutory per diem is an allowance, not a purchase, so there is no input VAT to reclaim on it.

A measured insight

Substring matching a country name is how a per diem gets quietly priced at another country's rate.

The first build resolved a destination by exact name, then ISO code, then country.includes(destination). A trip to Oman came back priced, in EUR, with no warning: "romania".includes("oman") is true, so it took Romania's 42.00 EUR diet. Oman is not one of the 34 countries this build bundles, so the correct answer was a refusal naming the gap. Instead the caller got a confident number, in the wrong currency, from a country 3,000 km away.

The fix is one line — the fallback is a prefix match, four characters or more — and it is asserted in test/adversarial.test.mjs. The general form is worth more than the fix: a fuzzy match is safe when a miss is cheap and expensive when a miss is silent. Here a miss produces a tax figure, so the fallback has to fail closed. The table being deliberately partial is exactly what makes the substring fallback dangerous: with a complete table the wrong row is a near miss, and with a partial one it is a row that should never have matched at all.

Privacy

Everything stays on your machine. Trips are JSON under ${XDG_DATA_HOME:-~/.local/share}/mcp-servers/per-diem/. The rate tables are files inside the package. There is no network call anywhere in this server, no account and no API key. License keys are verified offline.

License

MIT. Support: support@zovo.one

First five minutes

Three prompts that scored 3 of 3, measured in round 22, 2026-09-05. Paste one in as it is written.

I left Warsaw on Tuesday 5 May 2026 at 8am and got back on Thursday 7 May at 6pm. The trip was to Krakow, I stayed two hotel nights, and breakfast was provided on the first day. What per diem am I owed?

What it did, measured in round 22, 2026-09-05: One perdiem_calc returned PLN 123.75 of diet over three days, 33.75 plus 45.00 plus 45.00, and PLN 135.00 of lodging ryczalt at PLN 67.50 a night, PLN 258.75 in all.

Different question, UK now. On 12 May 2026 one of our people left at 7am and was still travelling at 11pm, so 16 hours, a UK domestic journey. Lunch was free that day. What does the HMRC benchmark scale rate give?

What it did, measured in round 22, 2026-09-05: One perdiem_calc returned GBP 16.67: the GBP 25.00 fifteen-hour band, ongoing at 8pm, less GBP 8.33 for the free lunch.

Now a US one on the GSA standard rate. Arrived 1 June 2026 at 10am Eastern, flew home 3 June at 4pm, so three calendar days and two nights in a hotel, no meals provided. What can we claim?

What it did, measured in round 22, 2026-09-05: One perdiem_calc returned USD 170.00 of M&IE on the FY2026 CONUS standard, USD 51.00 plus USD 68.00 plus USD 51.00, with the first and last day at 75 percent per FTR 301-11.101.

On the free tier for this path: Rate lookups and calculations are unlimited on every tier: the tables are public regulation, and metering the reading of a regulation would be charging for the tax authority's work. 5 trips saved per calendar month, counted by start date, and unlimited trip lists.

Set it up in your client

Exact config path, entry and caveats: Claude Desktop · Claude Code · Cursor · VS Code · Windsurf · Cline · Claude.ai and Claude Desktop connectors · all clients

Guides

How to track billable hours inside Claude Code and Cursor · Create an invoice PDF from a chat message with an MCP server · Ask questions about an Excel or CSV file from Cursor or Claude · Watch a product price with Claude and get told when it drops · What the free tier includes and what Pro adds · Log expenses and mileage in Claude, split VAT, rebill to an invoice · Convert currencies in Claude with real ECB rates, no API key · Generate Word proposals and contracts from a chat message · Find a meeting time across time zones without doing the arithmetic · Write a resume and a cover letter from chat, without inventing anything · Bill a retainer on a schedule without a billing SaaS · Assemble a contract from your own clause library, in chat · Connect MCP servers to Claude.ai, Claude Desktop, Cursor and VS Code without installing anything · Merge, split and stamp PDFs from chat, and why some come back as glyph numbers · Read a .ics calendar in Claude: free and busy, conflicts, and billable meetings · Run a kanban board in Claude, with time tracking on the same task · Resize, compress and watermark images from a chat message · Categorize and reconcile a bank CSV export from chat · Send a quote from chat, then turn the yes into an invoice · Put a SEPA payment QR code on an invoice from chat · Zip and unzip archives safely from Claude or Cursor · Client deposits and retainers from chat, applied to your real invoices · Per diem and travel allowances from chat, on the rate tables the tax authorities publish · Credit notes and purchase orders from chat, against your real invoices · One install, every server: the office-suite bundle · All guides