MCP Server · Mexico

The Mexican tax layer your agent is missing.

SAT calculations without hallucination: surcharges, ISR, CFDI, IMSS and payroll — deterministic and verified against the law. Connect it to Claude or your MCP client.

fiscal_recargos

amount 50,000 · due Feb-17 · paid Jun-20

months late: 5 (day-by-day, CFF 21)

surcharges: $5,175.00

TOTAL due: $55,175.00

// verified vs LIF 2026 Art. 11

 

The problem

A made-up tax number is a real liability.

Models hallucinate rates, and SAT values change every year.

01
Hallucination

The model invents the rate

Asking an LLM to compute surcharges or ISR from memory yields plausible but wrong numbers.

They age

Values change every year

UMA, ISR tariffs, surcharges, the Severance & Old-Age curve: it all moves. A hardcoded value is already wrong.

Deterministic

The math isn't done by the LLM

Here the number comes from a deterministic engine over verified current values — zero hallucination in the figure.

The tools

Ten deterministic calculators.

SAT compliance + payroll, verified against primary sources.

10

fiscal_recargos

Late-payment surcharges + inflation update (CFF 17-A/21).

fiscal_valores_vigentes

UMA, minimum wage, surcharge & installment rates, with source.

fiscal_calendario

Obligations and deadlines by regime (day 17 + non-working days).

fiscal_regimen_factores

Factors to choose a tax regime — informs, doesn't decide.

fiscal_cfdi_validar

Validate a CFDI 4.0's coherence before stamping.

fiscal_isr_estimado

Estimate annual ISR by regime (Art. 152 tariff).

fiscal_isr_retencion

Monthly salary withholding (Art. 96 − employment subsidy).

fiscal_imss

IMSS worker/employer contributions (2026 CyV curve, SBC, 25-UMA cap).

fiscal_aguinaldo

Year-end bonus: gross, exempt (30 UMA), taxable and ISR.

fiscal_finiquito

Severance or dismissal settlement, with indemnities (LFT).

Pricing

Try it free. Scale for $19.

No install. Connect the endpoint and go.

02
Free

$0 — to try

The current-values tool, free and keyless. 50 calculations/month with a free key.

Pro

$19 USD/mo

All 10 tools, unlimited. Your API key arrives by email on subscribe. Cancel anytime.

How to connect

One endpoint. Zero install.

Remote MCP (streamable-http). Works in Claude and any MCP client.

03
mcp · streamable-http

// endpoint

https://menteorama-fiscal-mcp.menteorama.workers.dev/mcp

 

// authorization

Authorization: Bearer mk_live_…

FAQ

Frequently asked

Is this tax advice?

No. It's informational and deterministic. Confirm every decision with your accountant before filing or paying.

Are the numbers current?

Yes. Every value is verified against official sources (LIF, CFF, LISR, Anexo 8 RMF, DOF) and kept up to date — not hardcoded by the model.

How do I connect it?

It's a remote MCP server (streamable-http). Add the endpoint to Claude or your MCP client with your API key in the Authorization: Bearer header.

Can I cancel anytime?

Yes. The Pro subscription is monthly and cancelable anytime; you revert to the Free plan automatically.

Calculate without hallucinating.

Verified, deterministic SAT numbers, inside your agent.

Subscribe — $19 USD/mo How to connect

Informational, not tax advice. Verify with your accountant.