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Corporation Tax Calculator

Estimate UK Corporation Tax, marginal relief, effective rate and key deadlines for accounting periods beginning on or after 1 April 2023.

UK · Non-ring-fence profits · 2026 rates

Corporation tax calculator

Estimate Corporation Tax, marginal relief, your effective rate and standard deadlines using the current HMRC rate bands.

Rates verified for 2026
Enter company tax figuresNothing is uploaded or stored.
1
Enter profitsUse tax-adjusted figures, not turnover or accounting profit.
GBP
After allowable costs, capital allowances, losses and reliefs.
GBP
Added to taxable profits to calculate augmented profits. Enter 0 if none.
2
Set accounting periodShort periods proportionately reduce the profit thresholds.
This version supports periods beginning on or after 1 April 2023.
A Corporation Tax accounting period cannot exceed 12 months.
3
Apply company circumstancesAssociated companies divide the thresholds; some companies cannot use the small-profits rate or marginal relief.
other companies
Enter the number of other associated companies for the period.
Choose no for a close investment-holding company or another ineligible case.
Adjusted lower limit£50,000
→
Marginal-relief band£50,000–£250,000
→
Adjusted upper limit£250,000
UK company tax guide

Estimate Corporation Tax with the correct profit band

This UK Corporation Tax calculator applies the small-profits rate, main rate or marginal-relief formula to taxable total profits. It also calculates augmented profits, divides the thresholds for associated companies, reduces them for a short accounting period and explains every step used.

Enter taxable profits—not turnover: Start with the Corporation Tax profit after tax adjustments, allowable expenses, capital allowances, brought-forward losses and other relevant reliefs. Use your accountant’s figure if available.

UK Corporation Tax rates for 2026

HMRC lists the following rates for non-ring-fence profits. The £50,000 and £250,000 limits assume a 12-month period and no associated companies; the calculator adjusts them when necessary.

Rates for Corporation Tax years starting 1 April
Profit positionTreatment2026 figure
At or below lower limitSmall-profits rate19%
Between the limits25% less marginal relief3/200 fraction
At or above upper limitMain rate25%

How the Corporation Tax calculation works

1

Find augmented profits

Taxable total profits + relevant exempt distributions

2

Adjust the limits

Base limit × short-period fraction ÷ total associated companies

3

Choose the rate band

Use 19% below the lower limit, 25% above the upper limit, or marginal relief between them.

4

Calculate marginal relief

(3/200 × (upper limit − augmented profits)) × (taxable profits ÷ augmented profits)

Worked examples

Small profits

£30,000 profit

£30,000 × 19% = £5,700

No associated companies, full 12-month period and no relevant distributions.
Marginal relief

£100,000 profit

£25,000 − £2,250 = £22,750

The effective rate is 22.75% when augmented profits equal taxable profits.
Main rate

£300,000 profit

£300,000 × 25% = £75,000

The profit is above the unadjusted £250,000 upper limit.

Associated companies and short accounting periods

The profit limits are divided by the number of associated companies including the company being calculated. With three other associated companies, the standard limits are divided by four: £12,500 and £62,500 for a full year. A period shorter than 12 months reduces the limits again in proportion to its length. Association can be complex where control, connected persons or changing ownership is involved, so confirm the number used.

How exempt distributions change marginal relief

Relevant exempt distributions increase augmented profits without increasing taxable total profits. This can move a company higher in the marginal-relief band or remove relief entirely. The formula therefore multiplies the initial relief amount by taxable profits divided by augmented profits. Enter only distributions that belong in the statutory augmented-profit calculation.

Corporation Tax payment and return deadlines

A company with taxable profits within the standard payment regime normally pays Corporation Tax 9 months and 1 day after the accounting period ends. The Company Tax Return is normally due 12 months after period end. Companies within quarterly instalment rules pay earlier, and weekend or bank-holiday payment handling can affect when funds must reach HMRC. The calculator shows calendar dates but does not move them for non-working days.

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Frequently asked questions

What is the UK Corporation Tax rate in 2026?

For non-ring-fence profits, the small-profits rate is 19% at or below the adjusted £50,000 lower limit and the main rate is 25% at or above the adjusted £250,000 upper limit. Marginal relief produces a gradual transition between the two. Limits can be reduced for short periods and associated companies.

How is Corporation Tax marginal relief calculated?

The estimate starts with taxable total profits at the 25% main rate, then deducts relief using (3/200 × (adjusted upper limit − augmented profits)) × (taxable total profits ÷ augmented profits).

What are augmented profits?

Augmented profits are taxable total profits plus relevant exempt distributions. They are used to decide which rate band applies and to calculate marginal relief. Not every distribution is included, so use the amount your accountant identifies as relevant.

How do associated companies affect Corporation Tax?

The lower and upper profit limits are divided by the total number of associated companies including the company being calculated. If there are three other associated companies, the limits are divided by four.

Does this calculator deduct expenses or losses?

No. Enter taxable total profits after allowable expenses, capital allowances, losses and reliefs that apply. Accounting profit is not always the same as taxable profit.

When is Corporation Tax due?

Companies outside the quarterly-instalment regime usually pay 9 months and 1 day after the accounting period ends. The Company Tax Return is normally due 12 months after the end of that period. Larger companies can have earlier instalment dates.

Can I use this estimate for a Corporation Tax return?

Use it for planning only. It does not handle every adjustment, relief, group rule, ring-fence activity, bank surcharge, quarterly-instalment exception or period spanning an older tax regime. Confirm the return with current HMRC guidance or a qualified tax adviser.

Official sources and scope

Calculeter is independent and is not affiliated with HMRC. The estimate is for general information and planning, not tax, legal or accounting advice.