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 remote server, paid per call via x402 (USDC on Base). Capabilities that return a fact are billed from the first call; two discovery tools are free. No account, no API key to store, 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, tools + pricing) | GET https://app.qotien.fr/api/fiscal/v1/manifest |
| Registry | io.github.herve-coulon/tax-retirement |
Add it to any MCP client that supports a remote Streamable HTTP server, pointing at the endpoint above. Call qotien_capacites first (free) for the machine-readable catalog of tools, confidence levels, and prices.
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, which tax-reduction rates are in force this year. 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).
Two rules the engine never breaks:
- A figure never travels alone — every fact comes with its fiscal year, its legal sources, and a confidence level.
- A calculation, not a guess — when a rule or input is missing, the tool returns
non_calculable (an honest refusal), never an invented number and never an "average" rate.
Tools — 4 domains, 38 tools
MCP tool names are prefixed by domain (fiscal_*, retraite_*, simulateurs_*, referentiel_*); the same capabilities are reachable over REST under their bare names (tmi, per_gain, …). Each tool's tier is shown as [protocole] (free) · [barème] · [étude] · [optimiseur] (see Pricing).
Fiscal (income tax & wealth) — deterministic, confiance: fiable
fiscal_impot_revenu [barème] — income tax (progressive brackets, family quotient, décote)fiscal_tmi [barème] — marginal tax ratefiscal_cehr [barème] — exceptional contribution on high incomes (optional rfr_n1 / rfr_n2 apply the exceptional-income smoothing of art. 223 sexies II-1)fiscal_prelevements_sociaux [barème] — social-levy rate by income type (17.2 % vs 18.6 %)fiscal_surtaxe_pv_immobiliere [barème] — real-estate capital-gains surtaxfiscal_per_plafond [barème] — PER deduction ceiling (N-1 PASS for employees, N for self-employed)fiscal_plus_value_immobiliere [étude] — real-estate capital gain (holding-period abatements; acquisition_gratuite for inherited or gifted property: actual costs only, no 7.5 % flat allowance; quote_part + valeur_pleine_propriete apply the €15,000 exemption per co-owned or dismembered share in full ownership; terrain for land: no 15 % works allowance)fiscal_ifi [étude] — real-estate wealth tax (main residence −30 %; optional 75 % income cap, art. 979, computed on gross income: dividends before the 40 % allowance, flat-tax income included)fiscal_foncier_regime [étude] — unfurnished rental: micro-foncier vs actual-expense regime (household tax Δ)fiscal_lmnp_regime [étude] — furnished rental (LMNP): micro-BIC vs actual regime with depreciation (household tax Δ)fiscal_succession [étude] — inheritance duties per child (art. 777) and estimated saving of an early donationfiscal_cdhr [étude] — differential contribution on high incomes (20 % floor + décote)fiscal_per_gain [étude] — tax saved by a PER contribution: the total Δ (brackets + CEHR/CDHR), never "contribution × marginal rate"fiscal_niches_plafond [étude] — tax-reduction cap (art. 200-0 A) on reductions, with the excluded items handled (donations: 20 % limit on the total, Coluche €2,000 bracket outside it; JEI/JEIR: subscription ceilings by situation, 40 % rate for impact companies via variante: "impact", shared €50,000 cap for 2024-2028 via jei_reductions_anterieures)fiscal_flat_tax_vs_bareme [étude] — PFU vs progressive-scale comparisonfiscal_jeanbrun [étude] — Jeanbrun rental-investment depreciation (art. 31 I-1° i/j CGI); pass loyers_annuels, charges_annuelles, interets_annuels for the real saving (social levies only cut down to a zero net rental income, excess = global-income deficit capped at €10,700), otherwise a flagged theoretical maximum (hypothese_economie)
retraite_ps_pension [barème] (fiable) — pension gross→net (CSG/CRDS/CASA + 1 % health on the complementary part)retraite_regimes [barème] (fiable) — discovery: the computable schemes (32 covered)retraite_surcote_parentale [barème] (estime) — parental surcote (+1.25 %/qtr, max 5 %)retraite_pension_regime [étude] (fiable) — pension of one points-based scheme, with a plausibility guardretraite_pension_annuites [étude] (fiable) — pension of an annuity-based scheme (public sector, special schemes)retraite_pension_totale [étude] (fiable) — consolidated multi-scheme pension (the full career statement in one call), gross→netretraite_estimation [étude] (estime/partiel/non_calculable) — approximate pension from partial data, with a rangeretraite_rachat [étude] (fiable) — trimester buyback (VPLR): cost, net-of-tax, gain, ROIretraite_progressive [étude] (estime) — phased retirement (pension fraction + part-time)retraite_optimisation [optimiseur] (estime) — ranked menu of end-of-career levers (buyback, parental surcote, phased retirement, optimal age, cumul, SAM, PER) with gain/ROI/confidence
Simulateurs (wealth projections) — confiance: estime
simulateurs_girardin [barème] · simulateurs_rente_viagere [barème]simulateurs_scpi · simulateurs_scpi_credit · simulateurs_demembrement_scpi · simulateurs_apport_credit · simulateurs_rentabilite_reelle · simulateurs_private_equity — all [étude]
Référentiel (cite a dated fact) — confiance: sourcee
referentiel_valeur [barème] — one reference value, with its primary source, legal basis, and verification datereferentiel_recherche [barème] — search the reference by domain/keywordreferentiel_versions [protocole] — reference version + freshness (free)
qotien_capacites [protocole] — the catalog of tools, confidence levels, and prices (free; call this first)
Response contract
{
"ok": true,
"domaine": "retraite",
"capability": "pension_regime",
"confiance": "fiable",
"result": { "...": "..." },
"sources": ["references_officielles.json", "retraite_registre.js", "..."],
"millesime_fiscal": "2026",
"avertissement": "Deterministic indicative result — not personalized advice (CIF/DDA)."
}
confiance: fiable (deterministic, golden-tested) · estime/partiel (approximation, with a range) · sourcee (dated reference fact) · non_calculable (honest refusal instead of a made-up number).- A pension or a tax figure is never returned bare — confidence and sources travel with it.
Pricing — x402
Settlement in USDC on Base (eip155:8453). Prices are per successful call; a call that fails validation is not billed (settlement happens only on delivery).
| Tier | Price | Tools |
|---|
protocole | free | referentiel_versions, qotien_capacites |
barème | $0.05 | most fiscal_* rate/ceiling tools, retraite_ps_pension/regimes/surcote_parentale, referentiel_valeur/recherche, simulateurs_girardin/rente_viagere |
étude | $0.25 | studies: per_gain, ifi, cdhr, niches_plafond, retirement pensions, SCPI/PE simulators… |
optimiseur | $1.00 | retraite_optimisation |
An unpaid call gets HTTP 402 (x402 v2) on REST and MCP. On MCP the body carries both the x402 accepts field and a JSON-RPC -32002 error; a client that cannot pay sees a transport error (the call did not run). No anonymous free tier — to evaluate before paying, request a named trial key (header X-Qotien-Trial, issued manually). A euro-denominated commercial licence exists for application use (classic invoicing) — contact@qotien.fr.
Quick start
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"}'
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":"qotien_capacites","arguments":{}}}'
curl -s -X POST https://app.qotien.fr/api/fiscal/v1/mcp \
-H 'content-type: application/json' \
-d '{"jsonrpc":"2.0","id":3,"method":"tools/call","params":{"name":"retraite_pension_regime","arguments":{"code_regime":"agirc_arrco","points":750.07}}}'
An x402-capable client (or the x402-fetch / @x402/* libraries) handles the 402 → sign → settle → retry loop automatically.
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. Payment: x402 v2 (EIP-3009 transferWithAuthorization, USDC on Base).
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.
Part of Qotien — the reference for French personal-finance data: aggregated, sourced, dated, re-verified every year. Human-readable (qotien.fr/sources) and machine-readable (this MCP). Reference data under CC BY 4.0 — cite “Qotien — qotien.fr”.