# Duck Tax

> Free checker for UK micro-entity company accounts. Enter your figures, get the FRS 105 balance sheet they produce and every error worth fixing, before you pay anyone to file.

Duck Tax is a free tool for directors of UK micro-entity companies. It is not
an accountant, and it does not file anything.

## What it does

- Takes the figures a micro-entity has, typed or read from a bank statement
  or SparkPay revenue report, and derives the FRS 105 balance sheet.
- Flags figures an authority would reject before they reach a filing.
- Looks up a UK company from its Companies House number and fills in the name,
  registered office, directors, SIC codes, accounting period, the accounts
  deadline and the confirmation statement deadline.
- Detects from the register when the last accounts were filed dormant, and can
  fill a dormant filing in one click.
- Explains the resulting balance sheet in plain English.
- Produces a printable PDF to hand to an accountant or a filing product.
- Rebuilds the cost basis a US broker left blank on Form 1099-DA, by matching the
  form's disposals against the filer's own exchange and wallet records, and
  produces the Form 8949 rows with the correct box and adjustment plus a PDF
  evidence pack. At https://ducktax.com/1099-da.

## What it does not do

- It does not file accounts with Companies House or HMRC. Since 31 March 2026,
  UK accounts must be filed in iXBRL through commercial software. This tool does
  not do that and is not trying to.
- It is not accounting, tax or legal advice.
- The 1099-DA tool does not hold crypto, move it, or advise on what to hold, and
  it never invents a cost basis: a disposal it cannot evidence is reported as a
  gap for the filer to answer, not filled with a zero.
- It is not affiliated with, endorsed by or acting for HM Revenue & Customs,
  Companies House, the IRS or the ATO.
- It cannot supply a Corporation Tax UTR. That is not on any public register;
  HMRC issues it to the company.

## Privacy

The balance sheet is calculated in the browser. So is the whole 1099-DA tool:
the form, the exchange CSVs, the matching and both exports never leave the
visitor's machine, and nothing is stored. Figures are sent to a server only
when the visitor presses "Explain", and never with the company identifiers.

## MCP server

The whole tool is callable by AI assistants over the Model Context Protocol at
https://ducktax.com/api/mcp (Streamable HTTP, stateless). Tools cover deriving and
validating a balance sheet, register search and lookup, deadlines and late-filing
penalties, prior-year figures from filed accounts, bank statement categorisation,
plain-English explanations, and saved filings (with a bearer token from
https://ducktax.com/docs/mcp). All amounts are major currency units. It still files nothing.

## Pricing

The checker is free. Plans and current prices are published at
https://sparkpay.dev/spark/duck-tax, which https://ducktax.com/pricing redirects to.
No figures are repeated here, so this file cannot go stale against them.

## Pages

- [Checker](https://ducktax.com): the tool itself
- [1099-DA cost basis](https://ducktax.com/1099-da): rebuild the basis a broker left
  blank and get the Form 8949 rows
- [Pricing](https://sparkpay.dev/spark/duck-tax): plans and current prices
- [MCP server](https://ducktax.com/docs/mcp): setup, tokens and the full tool list
- [Privacy](https://ducktax.com/privacy)
- [Terms](https://ducktax.com/tos)

## Who runs it

Spark Games Ltd, registered in England and Wales, company number 15379140.