cz.freelax/tax-engine

by freelax.cz · remote · no sign-in to list tools · v1.0.0 · published by cz.freelax

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

Changes · 9

Compare Registry entry

14 tools: 9 change things and 5 only read.

Scanned Oct 21, 2026

Deletes or cancels0Claude Code: deny
Can't be undone0Claude Code: ask
Changes things9Claude Code: ask: see these tools
Only reads5Claude Code: allow: see these tools

3 checks matched something in the tool definitions. No finding is not a safety guarantee. How the checks work.

claude mcp add --transport http tax-engine https://freelax.cz/api/mcp

Findings

Matches of fixed checks, with the text they matched.

3 warn

Warncalc_set_aside
The server marks "calc_set_aside" read-only (readOnlyHint: true), and its own name, description or input give the class "write".
Matched text
annotations: {"readOnlyHint":true}; The name "calc_set_aside" says "set": a word for a change.
What this check looks for
Warnconvert_eur_czk
The server marks "convert_eur_czk" read-only (readOnlyHint: true), and its own name, description or input give the class "write".
Matched text
annotations: {"readOnlyHint":true}; The name "convert_eur_czk" says "convert": a word for a change.
What this check looks for
Warncheck_io_trigger
The server marks "check_io_trigger" read-only (readOnlyHint: true), and its own name, description or input give the class "write".
Matched text
annotations: {"readOnlyHint":true}; The name "check_io_trigger" says "trigger": a word for a change.
What this check looks for

Tools

Open a tool for its reasons and full description. Descriptions are the publisher's own words, shown as they are.

14 tools

Changes things 9Creates or changes something that can be changed back.Claude Code: ask

calc_flat_tax_settlementGiven 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 abo…No findings
Why it is in this group
- Nothing in its name or description says what it does, so it is counted as a write.
- The server marks it read-only (readOnlyHint: true), but an annotation never lowers a class.
Description, as the server wrote it
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).
Annotations the server declares
- readOnlyHint: true
calc_set_asideHow much of a monthly OSVČ income to set aside for Czech income tax, social and health insurance, and what remains safe to spend.1 finding
Why it is in this group
- The name "calc_set_aside" says "set": a word for a change.
- The server marks it read-only (readOnlyHint: true), but an annotation never lowers a class.
Findings
- Warn
  The server marks "calc_set_aside" read-only (readOnlyHint: true), and its own name, description or input give the class "write".
  Matched text
  annotations: {"readOnlyHint":true}; The name "calc_set_aside" says "set": a word for a change.
  What this check looks for
Description, as the server wrote it
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.
Annotations the server declares
- readOnlyHint: true
check_flat_tax_eligibilityScreens 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…No findings
Why it is in this group
- Nothing in its name or description says what it does, so it is counted as a write.
- The server marks it read-only (readOnlyHint: true), but an annotation never lowers a class.
Description, as the server wrote it
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.
Annotations the server declares
- readOnlyHint: true
check_io_triggerChecks 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,…1 finding
Why it is in this group
- The name "check_io_trigger" says "trigger": a word for a change.
- The server marks it read-only (readOnlyHint: true), but an annotation never lowers a class.
Findings
- Warn
  The server marks "check_io_trigger" read-only (readOnlyHint: true), and its own name, description or input give the class "write".
  Matched text
  annotations: {"readOnlyHint":true}; The name "check_io_trigger" says "trigger": a word for a change.
  What this check looks for
Description, as the server wrote it
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.
Annotations the server declares
- readOnlyHint: true
check_thresholdsChecks 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 paušáln…No findings
Why it is in this group
- Nothing in its name or description says what it does, so it is counted as a write.
- The server marks it read-only (readOnlyHint: true), but an annotation never lowers a class.
Description, as the server wrote it
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.
Annotations the server declares
- readOnlyHint: true
compute_yearComputes 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…No findings
Why it is in this group
- Nothing in its name or description says what it does, so it is counted as a write.
- The server marks it read-only (readOnlyHint: true), but an annotation never lowers a class.
Description, as the server wrote it
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.
Annotations the server declares
- readOnlyHint: true
convert_eur_czkConverts an EUR amount to CZK using the Czech National Bank daily exchange rate (the rate used for Czech tax purposes).1 finding
Why it is in this group
- The name "convert_eur_czk" says "convert": a word for a change.
- The server marks it read-only (readOnlyHint: true), but an annotation never lowers a class.
Findings
- Warn
  The server marks "convert_eur_czk" read-only (readOnlyHint: true), and its own name, description or input give the class "write".
  Matched text
  annotations: {"readOnlyHint":true}; The name "convert_eur_czk" says "convert": a word for a change.
  What this check looks for
Description, as the server wrote it
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.
Annotations the server declares
- readOnlyHint: true
czech_working_daysCzech 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 t…No findings
Why it is in this group
- Nothing in its name or description says what it does, so it is counted as a write.
- The server marks it read-only (readOnlyHint: true), but an annotation never lowers a class.
Description, as the server wrote it
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.
Annotations the server declares
- readOnlyHint: true
estimate_penaltyEstimates the Czech penalty/interest for a late payment or filing: repo rate + 8 p.p.No findings
Why it is in this group
- Nothing in its name or description says what it does, so it is counted as a write.
- The server marks it read-only (readOnlyHint: true), but an annotation never lowers a class.
Description, as the server wrote it
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.
Annotations the server declares
- readOnlyHint: true

Only reads 5Looks things up and changes nothing.Claude Code: allow

compare_regimesCompares 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…No findings
Why it is in this group
- The name "compare_regimes" says "compare": a word for reading.
Description, as the server wrote it
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.
Annotations the server declares
- readOnlyHint: true
get_filing_deadlinesDeadline for the Czech personal income tax return (DPFO) for a given tax year, per filing route: paper, self-filed electronic, or via tax advisor.No findings
Why it is in this group
- The name "get_filing_deadlines" says "get": a word for reading.
Description, as the server wrote it
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.
Annotations the server declares
- readOnlyHint: true
get_flat_tax_bandWhich 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.No findings
Why it is in this group
- The name "get_flat_tax_band" says "get": a word for reading.
Description, as the server wrote it
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.
Annotations the server declares
- readOnlyHint: true
get_prehled_deadlinesFiling 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 (…No findings
Why it is in this group
- The name "get_prehled_deadlines" says "get": a word for reading.
Description, as the server wrote it
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).
Annotations the server declares
- readOnlyHint: true
get_rule_sourceFor 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 Freela…No findings
Why it is in this group
- The name "get_rule_source" says "get": a word for reading.
Description, as the server wrote it
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.
Annotations the server declares
- readOnlyHint: true

This is not a safety rating, and no finding is not a safety guarantee. The groups and findings come from fixed checks of the tool definitions the server returned on the date shown, not from its code or what it does when called. How the checks work.

Install

Pinned to version 1.0.0. Values in angle brackets are yours to fill in.

claude mcp add --transport http tax-engine https://freelax.cz/api/mcp

Run in a terminal.

Claude Code permissions

Allow the reads, ask before a change, deny the deletes. Paste into .claude/settings.json.

.claude/settings.json

{
  "permissions": {
    "allow": [
      "mcp__tax-engine__compare_regimes",
      "mcp__tax-engine__get_filing_deadlines",
      "mcp__tax-engine__get_prehled_deadlines",
      "mcp__tax-engine__get_flat_tax_band",
      "mcp__tax-engine__get_rule_source"
    ],
    "ask": [
      "mcp__tax-engine__compute_year",
      "mcp__tax-engine__calc_set_aside",
      "mcp__tax-engine__calc_flat_tax_settlement",
      "mcp__tax-engine__estimate_penalty",
      "mcp__tax-engine__convert_eur_czk",
      "mcp__tax-engine__czech_working_days",
      "mcp__tax-engine__check_flat_tax_eligibility",
      "mcp__tax-engine__check_thresholds",
      "mcp__tax-engine__check_io_trigger"
    ],
    "deny": []
  }
}

Tools that only read are allowed, tools that change things ask first, tools that delete or cancel are denied. It assumes the server is installed as tax-engine. Review it before you use it.

Keep track

Get told when this server's tools change: a new tool, a new description, a new class.

https://anlyon.dev/servers/cz.freelax/tax-engine/changes.xml

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Source: MCP Registry. Synced Oct 21, 2026, 18:11 UTC.

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