About SoleKit
SoleKit is an independent, free set of invoicing and tax tools for UK sole traders, freelancers and small limited companies. It is funded by display advertising, asks for no account, and keeps your details in your own browser. Every figure comes from a named HMRC or GOV.UK source with a visible last-updated date.
Who runs the site?
SoleKit is run by The SoleKit team, a small UK team with a background in bookkeeping for sole traders and in building web tools. We are not accountants or tax advisers and nothing on the site is personal advice. The tools exist because the free options we found either hid the maths, added watermarks or asked for an email address before showing a PDF.
How is the site funded?
Display advertising only. There are no paid tiers, no affiliate links inside the tools and no data sales. Ads are placed around the tools, never inside the documents you download.
Where does the data come from?
Every rate, threshold and allowance lives in one versioned data file per tax year. A Budget change is a one-file edit, and the version and check date are printed in the footer of every page. The current files are:
| Tax year | Data version | Last checked | Sources |
|---|---|---|---|
| 2025/26 | 2025-26.3 | ||
| 2026/27 | 2026-27.2 | ||
| Late payment reference rates | calendar half-years | 30 June 2026 |
How are the calculators tested?
Each calculator has unit tests that compare its output with worked examples published by HMRC and GOV.UK, such as the 12,000-mile mileage example, the Flat Rate Scheme photographer example and the statutory interest example. The tests run on every change before the site is published. If you find a figure you believe is wrong, email us with the page link and we will check it against the source and fix it.
What do the tools do with my data?
The documents you create are built in your browser and never sent to our servers. Your business details, logo and last invoice number are saved in your browser’s local storage so you do not retype them, and you can clear them from any tool page. Read the privacy and cookies page for the details, including how advertising consent works.
Methodology notes
- Income tax uses the England, Wales and Northern Ireland bands by default; Scottish bands are available where a calculator offers a region switch.
- Self assessment estimates assume no other income, no student loan and a standard personal allowance unless you enter otherwise. They are planning estimates, not a return.
- Payslips use the standard 1257L code on a non-cumulative basis, which is what a one-off payslip can support. Payroll software applies cumulative codes across the year.
- Statutory interest uses the Bank of England base rate in force on 31 December or 30 June, as the Late Payment of Commercial Debts (Interest) Act 1998 requires, not the rate on the day.
- Rounding follows HMRC practice where it is specified and standard 2 decimal place rounding elsewhere.
How can I contact you?
Email hello@solekit.co.uk. Corrections, feature requests and questions about citing the site are all welcome. We cannot answer individual tax questions.