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Can Claude look up GSA per diem rates?

Not reliably from memory. GSA sets lodging and meals rates for hundreds of US areas each fiscal year, many change by month, and the new year starts every October 1, so the rate Claude remembers is often last year's. Connect the free IRS Mileage Rate and Per Diem server and Claude reads the FY2026 and FY2027 GSA rates by city or ZIP code, then totals a trip with the 75% first and last day rule.

Connect free, no token IRS mileage rate and per diem MCP server

What Claude does alone, and what needs the server

Claude on its own

  • Explains what per diem covers and how the 75% travel day rule works.
  • Adds up a trip once it has the daily rates.

With the IRS Mileage Rate and Per Diem server

  • GSA lodging and M&IE rates by city, county or ZIP for FY2026 and FY2027.
  • Monthly lodging seasons for areas that have them.
  • The IRS high-low rates and a deduction for meals already provided.

A real call to the live server

We sent this to the hosted server on 2026-11-03. The answer below is the server's own text, not a mock-up. Live values will differ when you ask.

You ask

What is the federal per diem for a 4-day trip to Chicago from November 16 to 19, 2026?

Tool call

calculate_trip_per_diem {"city":"Chicago","state":"IL","start_date":"2026-11-16","end_date":"2026-11-19"}

Server answer

4-day trip to Chicago, IL (2026-11-16 to 2026-11-19): lodging up to $696.00 for 3 nights, M&IE $322.00 ($92 a full day, $69 first and last day). Maximum per diem $1,018.00.

Connect it in 1 minute

One URL, no token, no account. In Claude.ai or Claude Desktop open Settings, then Connectors, then Add custom connector, and paste the URL.

Connector URL

https://irs-mileage-rate-per-diem-mcp.lipmichal.workers.dev/mcp

Claude Code

claude mcp add --transport http irs-mileage-rate-per-diem https://irs-mileage-rate-per-diem-mcp.lipmichal.workers.dev/mcp

Cursor (~/.cursor/mcp.json)

{
  "mcpServers": {
    "irs-mileage-rate-per-diem": {
      "url": "https://irs-mileage-rate-per-diem-mcp.lipmichal.workers.dev/mcp"
    }
  }
}

VS Code (.vscode/mcp.json)

{
  "servers": {
    "irs-mileage-rate-per-diem": {
      "type": "http",
      "url": "https://irs-mileage-rate-per-diem-mcp.lipmichal.workers.dev/mcp"
    }
  }
}

All 5 tools, sources and more prompts: IRS mileage rate and per diem MCP server · TaxBreakCalc self-employed set-aside calculator

Questions

Can Claude look up GSA per diem rates?
Not reliably from memory. GSA sets lodging and meals rates for hundreds of US areas each fiscal year, many change by month, and the new year starts every October 1, so the rate Claude remembers is often last year's. Connect the free IRS Mileage Rate and Per Diem server and Claude reads the FY2026 and FY2027 GSA rates by city or ZIP code, then totals a trip with the 75% first and last day rule.
Does it cover trips abroad?
No. It covers the continental US (CONUS) GSA rates only.
Can my employer pay up to these rates tax free?
Under Rev. Proc. 2019-48 an allowance up to the federal rate counts as substantiated, but you still need records of time, place and business purpose.
Is the server free?
Yes. The IRS Mileage Rate and Per Diem server is free at its hosted URL with no token, key or account. The source is open on GitHub.

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