Corporation Tax Calculator
Work out the corporation tax amount your limited company owes for 2026/27, including marginal relief between the two rates. Enter your profit and the calculator shows the tax, the effective corporation tax percentage, and the date the money is due.
Rates last checked 11 September 2026 · Tax year 2026/27
What is corporation tax? #
Corporation Tax is the tax a UK limited company pays on its profits. That is the short corporation tax definition, and it hides two things worth knowing straight away. The first is that there is no personal allowance: unlike Income Tax, where the first £12,570 is free, the first pound of company profit is taxable. The second is that the company pays it, not you. Money you then take out of the company as salary or dividends is taxed again in your own hands, which is why the salary versus dividend question exists at all.
The charge sits in the Corporation Tax Act 2010. When people search for the corporation tax act they are usually looking for one of two things in it: the rates in Part 3, or the marginal relief formula in Part 3 Chapter 3A. Both are below in plain English.
It applies to three kinds of profit. Trading profit from what the company actually does, investment income such as bank interest, and chargeable gains when the company sells an asset for more than it paid. They are added together and charged at the same rate.
Corporation tax rates for 2026/27 #
There are two corporation tax rates and one band in between where neither applies cleanly. This is what people mean by corporation tax bands or corporation tax brackets, although Corporation Tax does not work in slices the way Income Tax does. Your whole profit is charged at one rate, and which rate depends on where the profit lands.
| Profit | Corporation tax rate | What it is called |
|---|---|---|
| Up to £50,000 | 19% | Small profits rate |
| £50,001 to £249,999 | 19% to 25% | Marginal relief, 26.5% on each pound in the band |
| £250,000 and above | 25% | Main rate |
These corporation tax rates have not changed for 2026/27. The 19% and 25% figures and the two limits have been stable since April 2023, when the single 19% rate was split in two. The corporation tax level that catches people out is not either headline rate, it is the band between them.
The 26.5% nobody advertises #
Between £50,000 and £250,000 the company is charged at 25% and then given corporation tax marginal relief back. The arithmetic is:
Marginal relief = (£250,000 − your profit) × 3/200
The effect is that every extra pound of profit in that band costs 26.5p in tax, which is higher than the 25% main rate. Earning more moves you toward a higher corporation tax percentage overall, and the marginal cost of the pound that does it is the steepest in the whole system.
On £100,000 of profit: 25% of £100,000 is £25,000, marginal relief is (£250,000 − £100,000) × 3/200 = £2,250, so the corporation tax amount due is £22,750. That is an effective corporation tax percentage of 22.75%, not 19% and not 25%.
| Taxable profit | Corporation Tax | Effective rate |
|---|---|---|
| £25,000.00 | £4,750.00 | 19.00% |
| £50,000.00 | £9,500.00 | 19.00% |
| £75,000.00 | £16,125.00 | 21.50% |
| £100,000.00 | £22,750.00 | 22.75% |
| £150,000.00 | £36,000.00 | 24.00% |
| £200,000.00 | £49,250.00 | 24.63% |
| £250,000.00 | £62,500.00 | 25.00% |
| £500,000.00 | £125,000.00 | 25.00% |
A corporation tax marginal relief calculator #
The tool above doubles as a corporation tax marginal relief calculator. The relief is shown as its own line in the working rather than folded into the total, so you can see exactly what it is worth on your profit and how it changes if the profit moves.
Corporation tax rates 2025 and 2026, side by side #
Nothing changed. The corporation tax rates 2025 figures and the corporation tax rates 2026 figures are identical: 19% up to £50,000, 25% from £250,000, marginal relief in between. The structure has been stable since April 2023, so a page written in 2024 is still right on the headline numbers even where it is out of date on everything else.
The corporation tax marginal rate is the figure that is never published as a rate at all. It is 26.5% on each pound between the two limits, which is higher than the 25% main rate. That is the number to plan around if your profit sits in the band.
This corporation tax calculator UK tool applies those rates directly, and it is the same arithmetic a corporation tax calculator HMRC would run. Searched for as a corporation tax UK calculator or an HMRC corporation tax calculator, it is this page either way. The difference here is that the working is shown rather than hidden, and the associated company adjustment that most versions leave out is included.
Associated companies divide the limits #
This is the single biggest reason a corporation tax calculator gives the wrong answer. The £50,000 and £250,000 limits are not per company. They are divided by the number of associated companies plus one.
One other company under common control and the small profits limit becomes £25,000, with the main rate limit at £125,000. Three other companies and the small profits limit is £12,500. A company making £40,000 of profit pays 19% on its own and considerably more if it has a sibling, without its profit changing at all.
A company is associated if one controls the other, or if both are under the control of the same person or persons. Dormant companies are ignored. This catches family arrangements and property companies far more often than people expect, and it is worth getting right before the year end rather than after.
Group relief, and the Corporation Tax Act 2009 #
Corporation tax group relief lets a loss in one group company be surrendered against profits in another, which is often the single largest planning item for a group. It is separate from the corporation tax associated companies rule above: association shrinks your rate limits, group relief moves losses. A group can be caught by one and not the other.
On the legislation, the Corporation Tax Act 2009 covers what is taxable, chiefly trading income, loan relationships and intangibles. The Corporation Tax Act 2010 covers the rates and reliefs. People search for the corporation tax act 2009 expecting rates and find none, because the rates live in the 2010 Act and in later Finance Acts.
A short accounting period scales them too #
The limits assume a 12 month accounting period. A six month period halves them, a three month period quarters them. Companies most often hit this in their first year, when the first accounting period runs from incorporation to the first year end and is rarely exactly twelve months. The calculator above handles it through the period length field.
When corporation tax is due #
Corporation Tax runs the opposite way round to every other tax you will meet. You pay first and file afterwards.
- Payment is due 9 months and 1 day after the end of the accounting period.
- The Company Tax Return, the CT600, is due 12 months after the end of the period.
So a company with a 31 March year end must pay by 1 January and file by the following 31 March. The payment deadline arrives three months before the filing deadline, which means you are expected to know the corporation tax amount before you have formally declared it. Miss the payment date and HMRC charges interest at 7.75%, which is the Bank of England base rate plus 4 percentage points. That margin rose from 2.5 points on 6 April 2025.
Larger companies do not get the single payment date at all. Above £1.5 million of profit the tax is paid in four quarterly instalments, two of which fall before the accounting period has even ended. There is more on both in the guide to corporation tax deadlines and payment.
Losses, and corporation tax for small businesses #
A trading loss is not simply written off. Corporation tax losses carry back lets a loss be set against profits of the previous accounting period, which can produce a repayment of tax already paid rather than only relief against future profits.
That matters most to a company that had a good year followed by a bad one, because carrying back turns a loss into cash now instead of a deduction later. It is also why a loss-making year is still worth computing carefully rather than filing as a formality.
Corporation tax for small businesses is otherwise the same regime as for large ones: the same rates, the same marginal relief, the same deadlines. Size changes nothing until profits reach the quarterly instalment threshold, which is covered in corporation tax payment and deadlines.
What this calculator does not do #
It works out the tax on a profit figure you give it. It does not work out the profit, and that is the harder half of the job. Getting from your accounts to a taxable profit means adding back disallowable costs such as client entertaining and most depreciation, then deducting capital allowances, including the Annual Investment Allowance, full expensing and the 40% first-year allowance. It also does not handle losses carried in or back, R&D relief, group relief, Patent Box, or franked investment income in the associated company calculation.
For anything with those in it, the figure here is a good sense check and not a return. Filing itself needs HMRC's own service or corporation tax filing software, because the accounts and computations have to go in tagged as iXBRL and no calculator produces that.
The Corporation Tax rate UK companies pay #
There is no single Corporation Tax rate UK wide, which is why the question keeps coming back. Corporation tax in UK law has two rates and a band between them where the effective rate is higher than either.
The corporation tax threshold UK companies care about is £50,000.00, below which the small profits rate applies, and £250,000.00, above which the main rate applies in full. Between them marginal relief applies, and the corporation tax UK rate on that slice of profit is effectively 26.5%.
Corporation tax gov uk guidance sets the same rates out, and HMRC's corporation tax contact number is published there rather than here, because contact details change more often than the rates do.
Common questions #
What are the corporation tax rates for 2026/27?
The small profits rate is 19% on profits up to £50,000 and the main rate is 25% on profits from £250,000. Profits between the two carry marginal relief, which produces an effective 26.5% on each pound in that band and an overall rate somewhere between 19% and 25%.
How do I work out the corporation tax amount I owe?
Take your taxable profit. If it is £50,000 or less, multiply by 19%. If it is £250,000 or more, multiply by 25%. In between, multiply by 25% and then subtract marginal relief, which is the difference between £250,000 and your profit multiplied by 3/200.
What is the corporation tax percentage on £100,000 of profit?
On £100,000 with no associated companies and a full 12 month period, the tax is £22,750. That is an effective corporation tax percentage of 22.75%, because 25% of £100,000 is £25,000 and marginal relief takes off £2,250.
Does having other companies change my corporation tax?
Yes. The £50,000 and £250,000 limits are divided by the number of associated companies plus one. Two associated companies means the small profits limit is £25,000, so profit that would have been taxed at 19% is pushed into marginal relief.
When is corporation tax due?
Payment is due 9 months and 1 day after the end of your accounting period. The Company Tax Return is not due until 12 months after the end of the period, so the payment deadline arrives three months before the filing deadline.
What is corporation tax?
Corporation Tax is the tax a UK limited company pays on its profits, charged under the Corporation Tax Act 2010. It applies to trading profit, investment income and chargeable gains. Unlike Income Tax there is no personal allowance, so the first pound of profit is taxable.