Corporation Tax calculator
Work out what your limited company owes in Corporation Tax. Enter your turnover and expenses, and we'll apply the right rate – 19%, 25%, or somewhere in between if marginal relief applies – then show you when the money is due.
You'll see it called corporate tax, company tax, or just corp tax. In the UK it's all the same thing: the tax your limited company pays on its profits.
- 2026/27 HMRC rates
- Marginal relief included
- Associated companies
- Payment deadline
Your figures
Updates as you typeProfit after expenses and capital allowances – the figure that goes on your CT600.
365 days – a full 12 months, so you get the whole £50,000 and £250,000 thresholds.
Other companies under the same control as yours, not counting this one. On your own you keep the full £50,000 and £250,000.
Leave at 0 unless the company received dividends from a company it doesn't control. They aren't taxed, but they count towards the thresholds that decide your rate.
ANNA keeps this figure live all year, then files the CT600 for you.
File with ANNAUK Corporation Tax rates for 2026/27
Since April 2023 there hasn't been one Corporation Tax rate – there are two, plus a sliding scale between them. The calculator above picks the right band for you, but here's the full picture.
| Taxable profit | Rate | What it's called |
|---|---|---|
| £0 – £50,000 | 19% | Small profits rate |
| £50,001 – £250,000 | 19% – 25% | Main rate with marginal relief. The effective rate climbs gradually across the band, and every extra £1 of profit is taxed at 26.5%. |
| Over £250,000 | 25% | Main rate |
Thresholds are pro-rated if your accounting period is shorter than 12 months, and divided between associated companies.
How to calculate Corporation Tax
Corporation Tax is charged on profit, not on turnover. Your calculation starts with the profit in your accounts and takes four steps to get to the tax due. Here's how to work out Corporation Tax by hand, so you can check what the calculator is doing.
How is Corporation Tax calculated? The short version
Take your accounting profit, add back the costs HMRC doesn't allow, deduct your capital allowances, then apply 19% if the result is under £50,000 or 25% if it's over £250,000. Land in between and you pay 25% less marginal relief.
Start with your accounting profit
Take the profit before tax from your annual accounts: turnover minus your business costs. This is your starting point, not your sales figure. A company turning over £300,000 with £280,000 of costs pays tax on £20,000, not £300,000.
Add back the costs HMRC won't allow
Some things sit in your accounts as expenses but aren't deductible for tax. You add them back, which pushes your taxable profit up:
- Client entertaining – lunches, tickets, hospitality
- Depreciation – replaced by capital allowances in step 3
- Fines and penalties – parking tickets, late filing penalties
- Some legal fees – anything relating to capital purchases
Take off capital allowances
Bought equipment, tools, computers, or a van? You can't just expense them, but you can claim capital allowances instead. The Annual Investment Allowance covers up to £1 million of qualifying spend in a year, and full expensing lets companies deduct 100% of new plant and machinery. This is what replaces the depreciation you added back.
Cars don't work this way. They're excluded from the Annual Investment Allowance and from full expensing. Instead they go into a writing-down allowance pool, giving you 14% of the value a year for most cars and 6% for higher-emission ones. That main pool rate dropped from 18% to 14% on 1 April 2026, and an accounting period straddling that date gets a hybrid rate in between. A new zero-emission car still gets 100% up front, but only until 31 March 2027. Vans aren't cars for this purpose, so they do qualify for the Annual Investment Allowance.
What's left is your taxable profit – the number your Corporation Tax is actually based on.
Apply the rate, and marginal relief if it applies
Under £50,000 of taxable profit, you pay 19%. Over £250,000, you pay 25% on the lot. In between, you start at 25% and claim marginal relief to bring it back down:
Marginal relief = (£250,000 − your profit) × 3 ÷ 200Tax due = (profit × 25%) − marginal relief
Two companies, two very different rates
Both companies turn over the same amount. One lands under the £50,000 threshold, one doesn't.
| Neat Studio Ltd | Bolt Fabrication Ltd | |
|---|---|---|
| Accounting period | 12 months to 31 Mar 2026 | 12 months to 31 Mar 2026 |
| Associated companies | 0 | 0 |
| Turnover | £140,000 | £140,000 |
| Allowable expenses | £98,000 | £52,000 |
| Accounting profit | £42,000 | £88,000 |
| Add back: entertaining & depreciation | £3,000 | £9,000 |
| Less: capital allowances | £1,000 | £17,000 |
| Taxable profit | £44,000 | £80,000 |
| Rate band | 19% | Marginal |
| Tax at 25% before relief | – | £20,000 |
| Marginal relief | – | −£2,550 |
| Corporation Tax due | £8,360 | £17,450 |
| Effective rate | 19.0% | 21.8% |
| Profit after tax | £33,640 | £70,550 |
Bolt Fabrication's £17,000 of capital allowances pulled its taxable profit down by £17,000 – and saved it £4,505 in tax at the 26.5% marginal rate. Timing your equipment purchases matters.
What this calculator does and doesn't cover
It handles
- Small profits rate, main rate, and everything in the marginal relief band
- Add-backs for depreciation, entertaining, and fines
- Capital allowances, including the Annual Investment Allowance
- Accounting periods shorter than 12 months, with thresholds pro-rated
- Periods of account over 12 months, split into separate Corporation Tax periods
- Associated companies splitting the £50,000 and £250,000 thresholds
- Your payment deadline and filing deadline, one set per accounting period
- Dividends from outside your group, through the augmented profits test
It doesn't handle
- R&D tax relief and the enhanced deductions that come with it
- Losses carried back or forward from other years
- Group relief, and losses surrendered between companies in a group
- Chargeable gains on selling property or investments
- Patent Box, creative industry reliefs, and other specialist claims
- Accounting periods that started before 1 April 2023
Treat the result as a solid estimate for cash-flow planning, not a filed figure. If any of the right-hand column applies to you, the number on your CT600 will be different.
Your books stay tidy. Corporation Tax files itself.
You've got a number. Now someone has to turn it into a CT600, match it to a set of annual accounts, and file both with HMRC and Companies House. That's the bit ANNA does for you.