Corporation Tax Calculator (FY2026)
Enter your company’s taxable profit to see the Corporation Tax due, your effective rate, and how marginal relief works if profits fall between £50,000 and £250,000. The result shows the exact relief arithmetic, so you can see why an extra pound of profit in the middle band costs 26.5p rather than 25p.
How it works
For the financial year 2026 (1 April 2026 – 31 March 2027) there are two rates: the small profits rate of 19% on profits up to £50,000, and the main rate of 25% on profits over £250,000 — both set by the Finance Act 2025.
Between the limits, marginal relief bridges the gap: tax = profit × 25% − (£250,000 − profit) × 3/200. A company with £100,000 profit pays £25,000 − £2,250 = £22,750, an effective rate of 22.75%.
Another worked example at the lower end: £60,000 of profit gives £60,000 × 25% = £15,000, minus relief of (£250,000 − £60,000) × 3/200 = £2,850, so £12,150 is due — an effective rate of 20.25%. The effective rate climbs smoothly from 19% at £50,000 to 25% at £250,000, and the calculator shows it for your own figure alongside the tax.
The marginal band creates a hidden 26.5% rate on each extra pound between £50k and £250k — every £1 of profit in that band costs 26.5p in tax, more than the main rate. The £50k/£250k limits are also divided by the number of associated companies and pro-rated for short accounting periods, which this calculator assumes away (single company, 12 months).
Who the standard bands do not fit: companies with associated companies (the limits are shared — two associated companies each get £25,000/£125,000), companies with accounting periods shorter than 12 months (limits shrink pro-rata), and close investment holding companies, which pay the 25% main rate regardless of profit level, so none of the marginal relief arithmetic applies to them.
Two practical points people miss: the tax is due 9 months and 1 day after the period ends — before the CT600 filing deadline of 12 months, so the payment date is the one to diary — and applying a flat 19% or 25% to a profit in the middle band is always wrong: a £150,000 profit pays £36,000 (an effective 24%), not £28,500 or £37,500.
FAQ
How much Corporation Tax will my company pay?
19% if taxable profit is £50,000 or less (£9,500 on exactly £50k), 25% if it is £250,000 or more, and a sliding effective rate in between: £75,000 profit → £16,125 (21.5%), £100,000 → £22,750 (22.75%), £150,000 → £36,000 (24%). Enter your own figure to get the exact number with the marginal relief arithmetic shown.
Why is the marginal rate 26.5% between £50,000 and £250,000?
Because marginal relief shrinks by 1.5p for every extra £1 of profit while the 25% headline applies to the whole amount — the combined effect is 26.5p of tax per additional £1 in the band. This matters for planning: a pension contribution or capital purchase that moves profit from £120,000 back towards £50,000 saves tax at 26.5%, not 25%.
Do the £50,000 and £250,000 limits apply to every company?
No — they are shared. The limits are divided by the number of associated companies (companies under common control): two associated companies each get £25,000/£125,000 limits. They are also pro-rated for accounting periods shorter than 12 months. Close investment holding companies pay the 25% main rate regardless of profit level.
When is Corporation Tax due?
For most companies, 9 months and 1 day after the end of the accounting period — a 31 December 2026 year-end pays by 1 October 2027. The CT600 return itself is due 12 months after the period ends. Companies with profits over £1.5m pay in quarterly instalments instead. Late payment interest runs from the due date, so the payment deadline matters more than the filing one.
How much tax on £200,000 of profit?
£200,000 × 25% = £50,000, minus marginal relief of (£250,000 − £200,000) × 3/200 = £750, so £49,250 — an effective rate of about 24.6%. This close to the £250,000 upper limit the relief is nearly exhausted; at £250,000 it reaches zero and the full 25% main rate applies to the whole profit.
Which financial year do these rates cover?
The financial year 2026 — 1 April 2026 to 31 March 2027 — as set by the Finance Act 2025: a 19% small profits rate up to £50,000, a 25% main rate above £250,000 and marginal relief at 3/200 in between. Corporation Tax rates are set per financial year in each Finance Act, so recheck the figures after each Budget.
Does the calculator handle associated companies?
No — it assumes a single company with a 12-month accounting period. If you control more than one company, divide the £50,000 and £250,000 limits by the number of associated companies before reading across: with two companies, marginal relief runs from £25,000 to £125,000 and the 26.5% marginal band bites at half the profit level. The formula itself is otherwise identical.