Qotien — French Tax & Retirement MCP

A sourced, dated calculation API for French personal taxation and retirement, exposed over MCP. Every response carries a confidence level, its legal sources, and the fiscal year — the engine never guesses a fact.

Hosted, public, free. No authentication. Rate-limited per IP. No personal data — inputs are abstract numbers (income, parts, pension points), never stored.

Connect

MCP endpoint (Streamable HTTP / JSON-RPC 2.0)	https://app.qotien.fr/api/fiscal/v1/mcp
REST	POST https://app.qotien.fr/api/fiscal/v1/calculate
Manifest (discovery)	GET https://app.qotien.fr/api/fiscal/v1/manifest

Add it to any MCP client that supports a remote Streamable HTTP server, pointing at the endpoint above.

Why call this instead of computing it yourself

A general LLM (or a code interpreter) can do arithmetic, but it does not reliably know the current, exact French rules — the 2026 income-tax brackets and décote thresholds, the value of an Agirc-Arrco or CARMF pension point, the reversion rate of each fund. It will produce a confident, wrong number. Qotien is up to date, sourced, and re-verified against primary sources at every release — the value where a tax or pension error is unacceptable (fintech, insurtech, advisory tools, wealth-management software).

Tools — 2 domains, 10 tools

Fiscal (income tax & wealth) — deterministic, confiance: fiable

• fiscal_impot_revenu — income tax (progressive brackets, family quotient, décote)
• fiscal_tmi — marginal tax rate
• fiscal_cehr — exceptional contribution on high incomes
• fiscal_prelevements_sociaux — social-levy rate by income type
• fiscal_surtaxe_pv_immobiliere — real-estate capital-gains surtax

Retirement — variable confidence, never a bare figure

• retraite_ps_pension (fiable) — pension gross→net (CSG/CRDS/CASA + 1% health on the complementary part)
• retraite_pension_regime (fiable) — pension of one points-based scheme (28 funds) with a plausibility guard
• retraite_pension_totale (fiable) — consolidated multi-scheme pension (the full career statement in one call), gross→net
• retraite_regimes (fiable) — discovery: the computable schemes
• retraite_estimation (estime/partiel/non_calculable) — approximate pension from partial data, with a range and a confidence level

Response contract

{
  "ok": true,
  "domaine": "retraite",
  "confiance": "fiable",
  "result": { "...": "..." },
  "sources": ["references_officielles.json v0.6.0", "retraite_registre.js", "..."],
  "millesime_fiscal": "2026",
  "avertissement": "Deterministic indicative result — not personalized advice (CIF/DDA)."
}

• confiance: fiable (deterministic, golden-tested) · estime/partiel (approximation) · non_calculable (honest refusal instead of a made-up number).
• A pension is never returned as a bare number — confidence and sources travel with it.

Quick start

# List tools
curl -s -X POST https://app.qotien.fr/api/fiscal/v1/mcp \
  -H 'content-type: application/json' \
  -d '{"jsonrpc":"2.0","id":1,"method":"tools/list"}'

# Agirc-Arrco pension: 750.07 points → 1079 €/year (confiance: fiable, sources attached)
curl -s -X POST https://app.qotien.fr/api/fiscal/v1/mcp \
  -H 'content-type: application/json' \
  -d '{"jsonrpc":"2.0","id":2,"method":"tools/call","params":{"name":"retraite_pension_regime","arguments":{"code_regime":"agirc_arrco","points":750.07}}}'

# REST — income tax for a 50 000 € household, 1 part
curl -s -X POST https://app.qotien.fr/api/fiscal/v1/calculate \
  -H 'content-type: application/json' \
  -d '{"capability":"impot_revenu","input":{"revenu_net_imposable":50000,"parts":1}}'

Protocol

MCP 2025-06-18. Methods: initialize, tools/list, tools/call, ping. Transport: JSON-RPC 2.0 over HTTP POST; the endpoint also serves a keepalive SSE stream on GET (Accept: text/event-stream) for clients that open the server→client channel.

Disclaimer

Results are deterministic indicative computations based on the French tax & social-security reference for the stated fiscal year. They are the raw output of a calculation engine and do not constitute personalized financial advice within the meaning of French CIF/DDA regulation.

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Part of Qotien — the reference for French personal-finance data: aggregated, sourced, dated, re-verified every year. Human-readable (qotien.fr) and machine-readable (this MCP).