About Business Tax Calc
Free UK business tax calculators that show their working, so you can see exactly how your number was reached.
Why this site exists
Most tax calculators give you a number and nothing else. That's fine until the number looks wrong, or your accountant's figure is different, and you have no way of telling why. Plenty of them also skip the rules that change the answer for real companies: marginal relief, associated companies, short accounting periods and periods that cross 1 April.
Business Tax Calc does it the other way round. Every calculator shows each step of the working, uses HMRC's published rates, and is checked against published worked examples. If you want to know how a figure was reached, it's on the page.
We're starting with limited companies, beginning with the corporation tax calculator, and adding tools for the self-employed and business finance after that.
Who builds it
I'm a software engineer with 10 years of experience and a BS Software Engineering degree from COMSATS University, where I graduated in 2016. I also run GoArtisans, a software and digital marketing agency.
Much of my work is in finance. I build and maintain loan management software for a UK alternative lender, where getting calculations right to the penny is part of the job. Business Tax Calc applies the same habits to tax: the rules go in one place, every result is tested, and nothing is rounded until the end.
How we keep the calculators accurate
Official rates only
Rates and limits come from HMRC's figures on gov.uk, and we check them again after every Budget and before each new tax year.
Tested against published examples
Each calculator is checked against worked examples from professional bodies such as ACCA. The results are on our methodology page.
Working shown
Every result comes with the steps behind it, so you or your accountant can check it line by line.
I'm not an accountant, and the calculators give estimates, not tax advice. For decisions that matter, use the results as a starting point for a conversation with a qualified accountant.
Independent and free
Business Tax Calc is independent and has no connection to HMRC or any government body. The calculators are free to use, with no sign-up. To pay for running the site, some pages may show adverts or recommend products we earn a commission from. Those links are always labelled, and they never change a calculator's result.
Get in touch
Spotted an error, or think a calculator is missing something? Contact us with the details. Reports of mistakes are checked first and fixed as a priority.
Last updated 2 November 2026