calc_flat_tax_settlement

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).

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

Input schema (JSON)

{
  "type": "object",
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "required": [
    "currentBand",
    "actualAnnualIncome"
  ],
  "properties": {
    "currentBand": {
      "enum": [
        "band1",
        "band2",
        "band3"
      ],
      "type": "string",
      "description": "Band actually paid during the year"
    },
    "isProjection": {
      "type": "boolean",
      "default": false,
      "description": "True for a mid-year projection instead of a final settlement"
    },
    "monthsInRegime": {
      "type": "integer",
      "default": 12,
      "maximum": 12,
      "minimum": 1
    },
    "flatRatePercent": {
      "anyOf": [
        {
          "type": "number",
          "const": 0.4
        },
        {
          "type": "number",
          "const": 0.6
        },
        {
          "type": "number",
          "const": 0.8
        }
      ],
      "description": "Flat-rate expense percentage as a decimal: 0.4 (other business), 0.6 (most freelancers / živnost volná), 0.8 (craft trades)"
    },
    "actualAnnualIncome": {
      "type": "number",
      "maximum": 100000000,
      "minimum": 0
    }
  },
  "additionalProperties": false
}

calc_set_aside

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.

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Argument	Type	Description
taxRegime	string
activityType	string
advanceExempt	boolean
monthlyIncome*	number	Gross monthly business income in CZK (§ 7 ZDP)
flatRatePercent	any	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

check_flat_tax_eligibility

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.

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Argument	Type	Description
activityType	string
annualIncome*	number	Expected annual business income in CZK
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

Input schema (JSON)

{
  "type": "object",
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "required": [
    "annualIncome"
  ],
  "properties": {
    "activityType": {
      "enum": [
        "main",
        "secondary"
      ],
      "type": "string"
    },
    "annualIncome": {
      "type": "number",
      "maximum": 100000000,
      "minimum": 0,
      "description": "Expected annual business income in CZK"
    },
    "citizenshipType": {
      "enum": [
        "eu",
        "non_eu_public",
        "non_eu_private"
      ],
      "type": "string",
      "description": "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": {
      "type": "boolean",
      "description": "Full VAT payer (plátce DPH). Identifikovaná osoba is NOT blocking."
    },
    "publicHealthStatus": {
      "enum": [
        "public",
        "outside",
        "unknown"
      ],
      "type": "string"
    },
    "rentalAnnualIncome": {
      "type": "number",
      "maximum": 100000000,
      "minimum": 0
    }
  },
  "additionalProperties": false
}

check_io_trigger

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.

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Argument	Type	Description
today	string	Evaluation date; defaults to today
vatStatus*	string	Current VAT status of the OSVČ
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)
foreignServicePurchase*	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
foreignServicePurchaseConfirmedAt	string

check_thresholds

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.

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Argument	Type	Description
annualIncome*	number

Input schema (JSON)

{
  "type": "object",
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "required": [
    "annualIncome"
  ],
  "properties": {
    "annualIncome": {
      "type": "number",
      "maximum": 100000000,
      "minimum": 0
    }
  },
  "additionalProperties": false
}

compare_regimes

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.

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Argument	Type	Description
isMarried	boolean
deductions	object
annualIncome*	number	Gross annual business income in CZK
hasChildUnder3	boolean
flatRatePercent	any	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)

Input schema (JSON)

compute_year

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.

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Argument	Type	Description
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

convert_eur_czk

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.

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Argument	Type	Description
amountEur*	number	Amount in EUR

Input schema (JSON)

{
  "type": "object",
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "required": [
    "amountEur"
  ],
  "properties": {
    "amountEur": {
      "type": "number",
      "maximum": 1000000000,
      "description": "Amount in EUR",
      "exclusiveMinimum": 0
    }
  },
  "additionalProperties": false
}

czech_working_days

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.

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Argument	Type	Description
date	string	Optional date (YYYY-MM-DD) to test for working-day status
year*	integer

Input schema (JSON)

{
  "type": "object",
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "required": [
    "year"
  ],
  "properties": {
    "date": {
      "type": "string",
      "format": "date",
      "pattern": "^(?:(?:\\d\\d[2468][048]|\\d\\d[13579][26]|\\d\\d0[48]|[02468][048]00|[13579][26]00)-02-29|\\d{4}-(?:(?:0[13578]|1[02])-(?:0[1-9]|[12]\\d|3[01])|(?:0[469]|11)-(?:0[1-9]|[12]\\d|30)|(?:02)-(?:0[1-9]|1\\d|2[0-8])))$",
      "description": "Optional date (YYYY-MM-DD) to test for working-day status"
    },
    "year": {
      "type": "integer",
      "maximum": 2030,
      "minimum": 2020
    }
  },
  "additionalProperties": false
}

estimate_penalty

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.

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Argument	Type	Description
dueDate	string	Original due date (YYYY-MM-DD); anchors the correct half-year repo rate
owedAmount*	number	Outstanding amount in CZK
daysOverdue*	integer
obligationType*	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)
gracePeriodActive	boolean

Input schema (JSON)

{
  "type": "object",
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "required": [
    "obligationType",
    "owedAmount",
    "daysOverdue"
  ],
  "properties": {
    "dueDate": {
      "type": "string",
      "format": "date",
      "pattern": "^(?:(?:\\d\\d[2468][048]|\\d\\d[13579][26]|\\d\\d0[48]|[02468][048]00|[13579][26]00)-02-29|\\d{4}-(?:(?:0[13578]|1[02])-(?:0[1-9]|[12]\\d|3[01])|(?:0[469]|11)-(?:0[1-9]|[12]\\d|30)|(?:02)-(?:0[1-9]|1\\d|2[0-8])))$",
      "description": "Original due date (YYYY-MM-DD); anchors the correct half-year repo rate"
    },
    "owedAmount": {
      "type": "number",
      "maximum": 100000000,
      "minimum": 0,
      "description": "Outstanding amount in CZK"
    },
    "daysOverdue": {
      "type": "integer",
      "maximum": 3650,
      "minimum": 0
    },
    "obligationType": {
      "enum": [
        "health",
        "social",
        "tax_advance",
        "pausal",
        "pausal_oznameni",
        "pausal_doplatek",
        "tax_return",
        "prehled_social",
        "prehled_health",
        "annual_social"
      ],
      "type": "string",
      "description": "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)"
    },
    "gracePeriodActive": {
      "type": "boolean",
      "default": false
    }
  },
  "additionalProperties": false
}

get_filing_deadlines

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.

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Argument	Type	Description
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)
taxYear*	integer	The tax year the return is FOR (e.g. 2025 return is filed in 2026)

Input schema (JSON)

{
  "type": "object",
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "required": [
    "taxYear"
  ],
  "properties": {
    "route": {
      "enum": [
        "standard_deadline",
        "self_electronic_extension",
        "advisor_extension"
      ],
      "type": "string",
      "description": "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)"
    },
    "taxYear": {
      "type": "integer",
      "maximum": 2030,
      "minimum": 2020,
      "description": "The tax year the return is FOR (e.g. 2025 return is filed in 2026)"
    }
  },
  "additionalProperties": false
}

get_flat_tax_band

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.

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Argument	Type	Description
annualIncome*	number
flatRatePercent	any	Flat-rate expense percentage as a decimal: 0.4 (other business), 0.6 (most freelancers / živnost volná), 0.8 (craft trades)

Input schema (JSON)

{
  "type": "object",
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "required": [
    "annualIncome"
  ],
  "properties": {
    "annualIncome": {
      "type": "number",
      "maximum": 100000000,
      "minimum": 0
    },
    "flatRatePercent": {
      "anyOf": [
        {
          "type": "number",
          "const": 0.4
        },
        {
          "type": "number",
          "const": 0.6
        },
        {
          "type": "number",
          "const": 0.8
        }
      ],
      "default": 0.6,
      "description": "Flat-rate expense percentage as a decimal: 0.4 (other business), 0.6 (most freelancers / živnost volná), 0.8 (craft trades)"
    }
  },
  "additionalProperties": false
}

get_prehled_deadlines

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).

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Argument	Type	Description
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)
taxYear*	integer

Input schema (JSON)

{
  "type": "object",
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "required": [
    "taxYear"
  ],
  "properties": {
    "route": {
      "enum": [
        "standard_deadline",
        "self_electronic_extension",
        "advisor_extension"
      ],
      "type": "string",
      "description": "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)"
    },
    "taxYear": {
      "type": "integer",
      "maximum": 2030,
      "minimum": 2020
    }
  },
  "additionalProperties": false
}

get_rule_source

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.

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Argument	Type	Description
topic*	string
locale	string

Input schema (JSON)

{
  "type": "object",
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "required": [
    "topic"
  ],
  "properties": {
    "topic": {
      "enum": [
        "pausalni_dan",
        "identifikovana_osoba",
        "dph_registrace",
        "zalohy",
        "prehledy",
        "penale",
        "danove_pasmo_23",
        "vedlejsi_cinnost"
      ],
      "type": "string"
    },
    "locale": {
      "enum": [
        "en",
        "cs"
      ],
      "type": "string",
      "default": "en"
    }
  },
  "additionalProperties": false
}

Tax Engine

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calc_flat_tax_settlement Read-only

Tax Engine

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calc_flat_tax_settlement Read-only

Tools (14)