# OSVcalc (remote · osvcalc.cz)

Czech OSVČ tax calculator: income tax, social and health insurance, VAT, paušální daň.

- Trust score: 26/100 (low)
- Change this week: 0
- Registry status: active
- Liveness: live
- Owner verified: no
- Last scored: 2026-11-05

## Components

- remote · `osvcalc.cz`: 26/100 (this document), [markdown](https://verifymcp.io/servers/cz-osvcalc-osvcalc/api-mcp.md), [page](https://verifymcp.io/servers/cz-osvcalc-osvcalc/api-mcp)

## Channel facts

- Endpoint: `https://osvcalc.cz/api/mcp`
- Transports: `streamable-http`
- Auth: `none`
- Version: `1.0.1`

## Trust breakdown

How this component scores in each security and reliability category. Every signal is checked automatically against the live server, and we only credit what we can confirm. Scores are 0–100 per category. Scoring method: https://verifymcp.io/docs/scoring (what has changed: https://verifymcp.io/docs/scoring/changelog)

Scored 2026-11-05.

- **Endpoint Security**: 66/100
  - The endpoint's TLS certificate is valid, in date, and uses a strong key.
  - Authorisation not yet verified: we couldn't confirm whether this endpoint requires it.
  - HTTPS is enforced; there's no plaintext access path.
  - The HSTS (Strict-Transport-Security) header is present.
  - DNSSEC is configured correctly; the domain's records validate against the full chain to the root.
- **Transport & Reachability**: 0/100
  - Transport check failed: declared streamable-http, but the endpoint returned HTTP 402.
- **Schema Quality & AI Usability**: 0/100
  - Schema not yet verified: we couldn't read the endpoint's schema, or could read only part of its tool list.
- **Stability & Change Management**: 0/100
  - Stability not yet verified: not enough scan history yet (needs a 30-day window).
- **Tool Coverage**: 0/100
  - Tool coverage not yet verified: we couldn't read the endpoint's tools, or could read only part of the list.
- **Tool Safety**: 0/100
  - Tool safety not yet verified: we couldn't read the endpoint's tools, or could read only part of the list.
- **Capabilities**: 0/100
  - Capabilities not yet verified: we couldn't read the endpoint's capabilities.

**Unverified: 5 categories.** Categories scored 0 because we could not verify them: authentication we do not have, an unreachable endpoint, or not enough scan history. We only credit what we can confirm.

## Install

### How do I install the OSVcalc MCP server?

OSVcalc is a hosted endpoint at https://osvcalc.cz/api/mcp, so there is nothing to install locally. Ready-made configuration for Claude, Cursor, VS Code, Codex and 5 more is on this page, copied from each client's own documentation.

### Claude

```bash
claude mcp add --transport http cz-osvcalc-osvcalc 'https://osvcalc.cz/api/mcp'
```

### Cursor

```json
{
  "mcpServers": {
    "cz-osvcalc-osvcalc": {
      "url": "https://osvcalc.cz/api/mcp"
    }
  }
}
```

### VS Code

```json
{
  "servers": {
    "cz-osvcalc-osvcalc": {
      "type": "http",
      "url": "https://osvcalc.cz/api/mcp"
    }
  }
}
```

### Codex

```toml
[mcp_servers.cz-osvcalc-osvcalc]
url = "https://osvcalc.cz/api/mcp"
```

### opencode

```json
{
  "$schema": "https://opencode.ai/config.json",
  "mcp": {
    "cz-osvcalc-osvcalc": {
      "type": "remote",
      "url": "https://osvcalc.cz/api/mcp",
      "enabled": true
    }
  }
}
```

### OpenClaw

```bash
openclaw mcp add cz-osvcalc-osvcalc --url 'https://osvcalc.cz/api/mcp' --transport streamable-http
```

### Hermes

```yaml
mcp_servers:
  cz-osvcalc-osvcalc:
    url: "https://osvcalc.cz/api/mcp"
```

### Netclaw

```json
{
  "McpServers": {
    "cz-osvcalc-osvcalc": {
      "Transport": "http",
      "Url": "https://osvcalc.cz/api/mcp"
    }
  }
}
```

### Vellum

```bash
assistant mcp add cz-osvcalc-osvcalc -t streamable-http -u 'https://osvcalc.cz/api/mcp'
```

### Other

```json
{
  "mcpServers": {
    "cz-osvcalc-osvcalc": {
      "type": "http",
      "url": "https://osvcalc.cz/api/mcp"
    }
  }
}
```

The mcpServers block is a cross-client convention. Remote transports vary, so check your client's docs.

## Changelog

Every change recorded for this component, newest first. Days that predate change tracking, or that we cannot explain, say so: "we were watching and nothing happened" and "we were not watching" are different claims.

### 2026-10-28 (score 26, −52)

- [security regression] Endpoint reachability: reachable → not serving MCP
- [security regression] Authorization: partial → unverified
- [security regression] Tool safety: pass → unverified
- [security regression] Stability: 0.50 → unverified
- [security regression] Transport: pass → fail
- [functional regression] Capabilities: pass → unverified
- [functional regression] Tool coverage: 100 → unverified
- [functional] First check of Schema quality: unverified

### 2026-10-26 (score 78, +1)

No change was recorded against any check on this day. Stability & Change Management went from 43 to 47. That category is still filling its 30-day observation window: 13 days of observed history at the previous scan, 14 at this one. The score rises as the window fills, whether or not the server changes.

### 2026-10-23 (score 77, +1)

No change was recorded against any check on this day. Stability & Change Management went from 33 to 37. That category is still filling its 30-day observation window: 10 days of observed history at the previous scan, 11 at this one. The score rises as the window fills, whether or not the server changes.

### 2026-10-21 (score 76, +1)

No change was recorded against any check on this day. Stability & Change Management went from 27 to 30. That category is still filling its 30-day observation window: 8 days of observed history at the previous scan, 9 at this one. The score rises as the window fills, whether or not the server changes.

### 2026-10-19 (score 75, +1)

No change was recorded against any check on this day. Stability & Change Management went from 20 to 23. That category is still filling its 30-day observation window: 6 days of observed history at the previous scan, 7 at this one. The score rises as the window fills, whether or not the server changes.

### 2026-10-17 (score 74, +1)

No change was recorded against any check on this day. Stability & Change Management went from 13 to 17. That category is still filling its 30-day observation window: 4 days of observed history at the previous scan, 5 at this one. The score rises as the window fills, whether or not the server changes.

### 2026-10-15 (score 73, +1)

- [functional] Server version: 1.0.0 → 1.0.1

### 2026-10-13 (score 72, +1)

- [functional improvement] Stability: unverified → 0.03

## MCP tools (2)

### `calculate_osvc_taxes` (~2946 tokens)

Calculate OSVČ taxes

Computes the 2026 income tax, social and health insurance doplatek for a Czech OSVČ (self-employed person), given what they've been paid so far this year and their situation. Also returns VAT registration status, a regime comparison, next year's advances, and a filing guide, with an explanation in the requested locale. Income counts when it's actually received into the account, not when it was invoiced (cash basis), so 'income' should only be what's been paid so far this year, and 'monthly' is a separate estimate of what's still expected between now and December. For example, income: 300000, currentMonth: 6, monthly: 50000 means 300 000 Kč has been received through June, and about 50 000 Kč/month is expected July through December on top of that. Call get_field_guide first if you need to explain an option to the user before they've decided on a value.

Input parameters:

- `actualExpenses` (number): What your business has actually spent so far this year, as long as you can prove it with an invoice or receipt: materials, goods you resell, subcontractors, rent for your workspace, software, busines…
- `credits` (object): Optional tax credits and deductions (children, disability, spouse, gifts, mortgage interest, insurance, loss carried forward). Every field defaults to none.
- `crossBorderServices` (boolean): Buying services from abroad (SaaS subscriptions, ads, hosting) or invoicing a business in another EU country can make you an identifikovaná osoba, with a 15-day registration deadline, even as a non-p…
- `currentMonth` (integer): The month the calculation is made for. Normally just leave it on the current month. Change it to see where you would stand in a different month, for example to plan ahead. Defaults to today's month.
- `employerTaxWithheld` (number): Souběh only: the income tax your employer has actually withheld from your salary this year (sražená záloha na daň, shown on your payslips or the potvrzení o zdanitelných příjmech). Leave unset to let…
- `employmentIncome` (number): Your gross pay (hrubá mzda) from your job so far this year: the amount before tax and insurance are taken off, as shown on your payslips. It's not the amount that lands in your account. It's added t…
- `expectedExpenses` (number): Your best guess of business costs still to be paid per month, from the month after currentMonth through December. Only used with taxRegime 'actual'; with 'pausal' expenses are a fixed percentage of i…
- `healthPaid` (number): What you actually paid in health insurance zálohy so far this year, if different from the assumed minimum. Leave unset to assume the minimum záloha was paid every month from startMonth onward.
- `income` (number): All the money your customers have paid you this year, from 1 January until today. Count only what actually arrived in your bank account (or was handed to you in cash). An invoice you sent doesn't cou…
- `insurer` (string): The user's health insurer, if known, so the filing guide can name the account to pay into. Leave empty if unknown.
- `invoices` (array): Alternative to entering income/currentMonth directly: a list of what was actually paid and when, letting the tool work out year-to-date income and the current month itself, correctly excluding an inv…
- `locale` (string): Language for the returned explanation text.
- `monthly` (number): Your best guess of income still to be paid into your account per month, from the month after currentMonth through December. Only feeds the year-end projection, not the amount owed right now.
- `nemocenske` (boolean): Sickness insurance is optional for OSVČ. If you pay it, you get sick pay (nemocenská) when illness stops you working, and it's required for maternity pay (peněžitá pomoc v mateřství). For sick pay y…
- `nemocenskeMonthly` (number): How much you pay each month, at least 243 Kč. You choose the amount yourself: it's 2.7 % of a base you pick (at least 9 000 Kč). Sick pay is calculated from that same base, so paying more means you g…
- `otherIncome` (number): Income besides this activity and employment: rent (§9), capital income such as interest or dividends (§8) and other income (§10), for the whole year. It only matters for paušální daň, which is closed…
- `paidNow` (boolean): Zálohy are payments you send every month in advance, so you don't have to pay everything at once after the year ends. As OSVČ you usually pay two of them: social insurance to your local social securi…
- `pausalBand`: Force a specific pásmo instead of letting it be chosen automatically from income and pausalRate. Only meaningful with taxRegime 'pausalTax', and only useful if you've already declared into a band and…
- `pausalPaid` (number): What you actually paid in paušální daň so far this year, if different from the assumed monthly rate (a band's rate can be revised retroactively mid-year, as pásmo 1's was in 2026). Leave unset to ass…
- `pausalRate` (string): You pay tax only on your profit: what you earned minus what your business cost you. The výdajový paušál is a shortcut. Instead of collecting receipts, the law lets you count a fixed percentage of you…
- `platceDph` (boolean): DPH is Czech VAT. A plátce DPH (VAT payer) adds VAT, usually 21 %, to most invoices, passes it on to the tax office and files regular VAT returns. In return, they can get back the VAT they paid on bu…
- `saved` (number): Money you have already put aside for this year's tax and insurance, for example in a savings account. It's subtracted from what you still need to set aside. Don't include the monthly zálohy you have…
- `socialPaid` (number): What you actually paid in social insurance zálohy so far this year, if different from the assumed minimum. Leave unset to assume the minimum záloha was paid every month from startMonth onward.
- `soubeh` (boolean): Tick this if you also have a job this year: a regular employment contract (pracovní poměr), or a DPP or DPČ agreement. Your wages and your business profit are added together in one tax return, so a…
- `startMonth` (integer): Month the business started, 1 to 12 (1 = January or earlier, i.e. self-employed for the whole year). Minimum social and health insurance is owed for every month from this one onward.
- `status` (string): This decides how much minimum insurance you have to pay. • Hlavní (main): the business is your main livelihood. You pay minimum social and health insurance every month, even if you earn little. • Z…
- `taxRegime` (string): This decides how your tax is worked out. There are three options: • Výdajový paušál: you're taxed as if a fixed percentage of your income went on business costs. No receipts needed. Usually the bett…
- `vedlejsiSocialAdvances` (boolean): Vedlejší only. Social insurance zálohy are owed only if you signed up for social insurance voluntarily, or from the year after the year your profit reached the rozhodná částka (117 521 Kč in 2026, §1…
- `vosPartner` (boolean): A partner in a veřejná obchodní společnost (general partnership) cannot use paušální daň (§7a). Tick this to have the calculator treat paušální daň as unavailable.

Output parameters:

- `comparison` (array): The same year under each regime, to compare them.
- `crossBorderServices` (boolean): As sent.
- `currentMonth` (number): The month the calculation is for, 1 to 12.
- `error` (boolean): True when currentMonth is before startMonth, so there is nothing to calculate. Every number is then 0.
- `gap`: Your `saved` amount compared with `total`. Null unless both saved and income are above 0.
- `hasIncome` (boolean): True when income is above 0.
- `hasUnpaid` (boolean): True when this month's zálohy are not paid yet (paidNow is false), so `unpaid` is filled in.
- `health` (object): Health insurance (zdravotní pojišťovna).
- `isDecember` (boolean): True when currentMonth is 12, so the figures are final and there is no projection.
- `nextYearAdvances`: Suggested advance payments for next year, based on this year's projected figures. Null without income.
- `notes` (object): Flags the explanation text draws on.
- `pausalTax`: Only for the paušální daň regime, otherwise null.
- `projection`: Year-end projection. Null in December.
- `regime` (string): The tax regime used: pausal (výdajový paušál), actual (skutečné výdaje) or pausalTax (paušální daň).
- `social` (object): Social insurance (ČSSZ).
- `status` (string): The activity status used, as sent.
- `tax` (object): Income tax so far.
- `taxBurden` (object): What tax and insurance take from your income.
- `total` (number): CZK to have set aside right now, on top of advance payments (zálohy) already paid: income tax so far plus the social and health insurance doplatek plus this month's unpaid zálohy. With paušální daň i…
- `unpaid`: This month's advance payments that are not paid yet. Null when everything is paid or nothing is due.
- `vat` (object): VAT registration status based on income so far.

### `get_field_guide` (~75 tokens)

Get OSVČ calculator field guide

Returns every field calculate_osvc_taxes accepts, grouped the way the web calculator groups them, with the same label and explanation shown in its tooltips. Use this to explain an option to the user before they've decided on a value, without running a calculation.

Input parameters:

- `locale` (string): Language for the returned explanation text.

Output parameters:

- `disclaimer` (string): The not-tax-advice notice to show alongside results.
- `fields` (array): Every input the calculation accepts.

## Diagnostics

Captured diagnostic sections: TLS, DNSSEC, Authorisation, Transports. The full working is on the page: https://verifymcp.io/servers/cz-osvcalc-osvcalc/api-mcp#diagnostics

## Score history

- 2026-11-05: 26
- 2026-11-04: 26
- 2026-11-03: 26
- 2026-11-02: 26
- 2026-11-01: 26
- 2026-10-31: 26
- 2026-10-30: 26
- 2026-10-29: 26
- 2026-10-28: 26
- 2026-10-27: 78
- 2026-10-26: 78
- 2026-10-25: 77
- 2026-10-24: 77
- 2026-10-23: 77
- 2026-10-22: 76
- 2026-10-21: 76
- 2026-10-20: 75
- 2026-10-19: 75
- 2026-10-18: 74
- 2026-10-17: 74
- 2026-10-16: 73
- 2026-10-15: 73
- 2026-10-14: 72
- 2026-10-13: 72
- 2026-10-12: 71

## Common questions

### What is the OSVcalc MCP server?

OSVcalc is an MCP server listed in the public MCP registry as cz.osvcalc/osvcalc. Czech OSVČ tax calculator: income tax, social and health insurance, VAT, paušální daň. This page covers its hosted endpoint (https://osvcalc.cz/api/mcp).

### Is the OSVcalc MCP server safe to use?

OSVcalc scores 26 out of 100 on VerifyMCP. That is a record of what we were able to check automatically, not an endorsement. The category breakdown on this page shows every signal behind the number, including the ones we could not confirm.

### What tools does the OSVcalc MCP server expose?

OSVcalc exposes 2 tools: calculate_osvc_taxes, get_field_guide. Their descriptions and schemas cost roughly 3,021 tokens of context every time the server is loaded.

### Does the OSVcalc MCP server require authentication?

Its publisher declares no required credentials for OSVcalc. We have not been able to confirm that against the live endpoint, and a server can require authorisation without declaring it here.

### Is the OSVcalc MCP server still maintained?

OSVcalc is still listed as active in the MCP registry. We last reached this channel on 5 November 2026. Those dates come from our own scans of the registry and the channel itself, not from anything the publisher announced.

## Links

- Remote endpoint: https://osvcalc.cz/api/mcp
- Website: https://osvcalc.cz/
- Changelog RSS feed: https://verifymcp.io/servers/cz-osvcalc-osvcalc/api-mcp.xml
- Changelog JSON feed: https://verifymcp.io/servers/cz-osvcalc-osvcalc/api-mcp.json
- HTML version of this page: https://verifymcp.io/servers/cz-osvcalc-osvcalc/api-mcp