cz.freelax/tax-engine

Measured conclusion: Deep-tested. L2 outcome: tools_ok.

Deterministic Czech OSVC tax tools for 2026: tax, insurance, deadlines, VAT and exchange rates.

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Copy this into your MCP client config:

{
  "mcpServers": {
    "tax-engine": {
      "url": "https://freelax.cz/api/mcp",
      "transport": "streamable-http"
    }
  }
}

Measured tools (14)

• compute_year read-only

  Computes a full Czech OSVČ tax year from personal facts: income tax with credits (children, spouse, deductions), social and health insurance, monthly set-aside, safe-to-spend, flat-tax band and regime-eligibility evaluation. All figures come from the deterministic Freelax engine, never from the model.

  Parameters:

  • hasZTP — boolean
  • taxYear — number — Only 2026 is supported because the engine currently has a 2026 ruleset
  • children — array
  • isMarried — boolean
  • isNewOsvc — boolean
  • taxRegime — string
  • deductions — object
  • activityType — string
  • targetRegime — string — Simulate a different regime without changing the stored facts
  • hasChildUnder3 — boolean
  • citizenshipType — string
  • disabilityGrade — string
  • flatRatePercent — Flat-rate expense percentage as a decimal (0.4 / 0.6 / 0.8)
  • isVATRegistered — boolean
  • isCzechTaxResident — boolean
  • publicHealthStatus — string
  • rentalMonthlyIncome — number
  • annualBusinessIncome — number — Exact annual business income in CZK; takes precedence over the monthly figure
  • employerCoversHealth — boolean
  • monthlyBusinessIncome — number — Gross monthly business income in CZK (§ 7 ZDP)
  • spouseIncomeUnderLimit — boolean — Spouse annual income under the sleva na manžela limit
  • hasReducedSocialMinimum — boolean
  • isExemptFromMonthlyZalohy — boolean

  Hints: read-only yes · destructive not declared · idempotent not declared · open-world not declared

• calc_set_aside read-only

  How much of a monthly OSVČ income to set aside for Czech income tax, social and health insurance, and what remains safe to spend. Supports mixed §7 business + §9 rental income and the paušální daň (flat tax) regimes.

  Parameters:

  • monthlyIncome (required) — number — Gross monthly business income in CZK (§ 7 ZDP)
  • taxRegime — string
  • activityType — string
  • advanceExempt — boolean
  • flatRatePercent — Flat-rate expense percentage as a decimal: 0.4 (other business), 0.6 (most freelancers / živnost volná), 0.8 (craft trades)
  • reducedMinimumBase — boolean — New OSVČ in the first 2 years (lower social minimum)
  • rentalMonthlyIncome — number — Monthly rental income in CZK (§ 9 ZDP); triggers the mixed-income calculation
  • employerCoversHealth — boolean
  • secondaryThresholdExceeded — boolean

  Hints: read-only yes · destructive not declared · idempotent not declared · open-world not declared

• compare_regimes read-only

  Compares the standard OSVČ regime against paušální daň (flat tax) for a yearly income, including tax credits that would be lost with the flat tax (children, spouse), and recommends the cheaper regime.

  Parameters:

  • annualIncome (required) — number — Gross annual business income in CZK
  • isMarried — boolean
  • deductions — object
  • hasChildUnder3 — boolean
  • flatRatePercent — Flat-rate expense percentage as a decimal: 0.4 (other business), 0.6 (most freelancers / živnost volná), 0.8 (craft trades)
  • numberOfChildren — integer
  • rentalAnnualIncome — number
  • spouseIncomeUnderLimit — boolean — Spouse annual income under the credit limit (sleva na manžela/manželku)

  Hints: read-only yes · destructive not declared · idempotent not declared · open-world not declared

• calc_flat_tax_settlement read-only

  Given the paušální daň band you paid and the actual annual income, computes whether you owe a doplatek (top-up), get a vratka (refund), or must exit the flat-tax regime (income above 2,000,000 CZK).

  Parameters:

  • currentBand (required) — string — Band actually paid during the year
  • actualAnnualIncome (required) — number
  • isProjection — boolean — True for a mid-year projection instead of a final settlement
  • monthsInRegime — integer
  • flatRatePercent — Flat-rate expense percentage as a decimal: 0.4 (other business), 0.6 (most freelancers / živnost volná), 0.8 (craft trades)

  Hints: read-only yes · destructive not declared · idempotent not declared · open-world not declared

• estimate_penalty read-only

  Estimates the Czech penalty/interest for a late payment or filing: repo rate + 8 p.p. for insurance and tax interest (3.5% H1 / 3.75% H2 2026), 3 grace days for tax payments, 200 CZK health aggregation floor and the 1,000 CZK tax non-assessment threshold. A dated estimate is rejected when its required rate period falls outside the implemented history.

  Parameters:

  • obligationType (required) — string — Obligation family: health/social insurance debt, tax_advance (záloha na daň), pausal (paušální daň payment), tax_return (late filing), prehled_* (late Přehled), annual_social (doplatek)
  • owedAmount (required) — number — Outstanding amount in CZK
  • daysOverdue (required) — integer
  • dueDate — string — Original due date (YYYY-MM-DD); anchors the correct half-year repo rate
  • gracePeriodActive — boolean

  Hints: read-only yes · destructive not declared · idempotent not declared · open-world not declared

• convert_eur_czk read-only

  Converts an EUR amount to CZK using the Czech National Bank daily exchange rate (the rate used for Czech tax purposes). Reports the rate, its publication date and whether a stale cached ČNB publication had to be used. Fails closed when no verified ČNB rate is available.

  Parameters:

  • amountEur (required) — number — Amount in EUR

  Hints: read-only yes · destructive not declared · idempotent not declared · open-world not declared

• get_filing_deadlines read-only

  Deadline for the Czech personal income tax return (DPFO) for a given tax year, per filing route: paper, self-filed electronic, or via tax advisor. Weekend and holiday shifts are applied.

  Parameters:

  • taxYear (required) — integer — The tax year the return is FOR (e.g. 2025 return is filed in 2026)
  • route — string — Filing route: standard_deadline = paper/no extension (1 April), self_electronic_extension = filed electronically after 1 April (+1 month), advisor_extension = filed by a tax advisor (1 July)

  Hints: read-only yes · destructive not declared · idempotent not declared · open-world not declared

• get_prehled_deadlines read-only

  Filing deadlines for the annual OSVČ Přehled o příjmech a výdajích for both social insurance (ČSSZ) and the health insurer, per tax-return filing route, plus the payment due date (8 calendar days after the filing deadline).

  Parameters:

  • taxYear (required) — integer
  • route — string — Filing route: standard_deadline = paper/no extension (1 April), self_electronic_extension = filed electronically after 1 April (+1 month), advisor_extension = filed by a tax advisor (1 July)

  Hints: read-only yes · destructive not declared · idempotent not declared · open-world not declared

• czech_working_days read-only

  Czech public holidays for a year (including movable Easter feasts) and, for a specific date, whether it is a working day and the next working day a statutory deadline would shift to.

  Parameters:

  • year (required) — integer
  • date — string — Optional date (YYYY-MM-DD) to test for working-day status

  Hints: read-only yes · destructive not declared · idempotent not declared · open-world not declared

• check_flat_tax_eligibility read-only

  Screens whether an OSVČ may enter or stay in the paušální daň (flat tax) regime: public health insurance participation (decisive for foreigners), VAT-payer status, income ceiling 2,000,000 CZK, side income and secondary activity. Returns reasons with severity.

  Parameters:

  • annualIncome (required) — number — Expected annual business income in CZK
  • activityType — string
  • citizenshipType — string — eu = EU/EEA citizen; non_eu_public = non-EU participating in Czech public health insurance (e.g. dočasná ochrana, employment); non_eu_private = non-EU with private/commercial insurance only
  • isVATRegistered — boolean — Full VAT payer (plátce DPH). Identifikovaná osoba is NOT blocking.
  • publicHealthStatus — string
  • rentalAnnualIncome — number

  Hints: read-only yes · destructive not declared · idempotent not declared · open-world not declared

• get_flat_tax_band read-only

  Which paušální daň band (pásmo 1/2/3) an annual income falls into given the expense flat-rate, the current monthly payment for that band, and the next income threshold to watch.

  Parameters:

  • annualIncome (required) — number
  • flatRatePercent — Flat-rate expense percentage as a decimal: 0.4 (other business), 0.6 (most freelancers / živnost volná), 0.8 (craft trades)

  Hints: read-only yes · destructive not declared · idempotent not declared · open-world not declared

• check_thresholds read-only

  Checks an annual income against the four statutory thresholds: VAT registration 2,000,000 CZK, immediate VAT registration 2,536,500 CZK, the 23% higher tax bracket, and the paušální daň eligibility ceiling. Reports approaching (90%), exceeded and remaining amounts.

  Parameters:

  • annualIncome (required) — number

  Hints: read-only yes · destructive not declared · idempotent not declared · open-world not declared

• check_io_trigger read-only

  Checks whether buying services from abroad (Google Ads, Meta, ChatGPT, hosting…) or selling services to EU businesses has made an OSVČ an identifikovaná osoba under § 6h/§ 6i ZDPH, with the 15-day registration deadline (§ 97) and fact-freshness handling. Verdict: ok / check / act_now.

  Parameters:

  • vatStatus (required) — string — Current VAT status of the OSVČ
  • foreignServicePurchase (required) — string — Foreign service purchases: none_confirmed = verified none, possible = maybe (e.g. runs online ads), qualifying_confirmed = a qualifying purchase from a non-CZ supplier is confirmed
  • today — string — Evaluation date; defaults to today
  • foreignSales — array — Year-to-date foreign client income for the sales-side (§ 6i) check
  • purchaseDate — string — Date of the qualifying purchase; drives the 15-day § 97 registration deadline
  • vatStatusConfirmedAt — string — When the VAT status was last confirmed (freshness window 180 days)
  • foreignServicePurchaseConfirmedAt — string

  Hints: read-only yes · destructive not declared · idempotent not declared · open-world not declared

• get_rule_source read-only

  For a Czech OSVČ tax topic, returns the governing rule with current values, primary-source citations (zákon, ČSSZ, VZP, Finanční správa) with verification dates, and related Freelax articles. Topics: pausalni_dan, identifikovana_osoba, dph_registrace, zalohy, prehledy, penale, danove_pasmo_23, vedlejsi_cinnost.

  Parameters:

  • topic (required) — string
  • locale — string

  Hints: read-only yes · destructive not declared · idempotent not declared · open-world not declared

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