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.
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%.
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).
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.