UK Corporation Tax Calculator (2026)

FAQs

UK Corporation Tax FAQs

What are the UK Corporation Tax rates in 2026?

The small profits rate is 19% on taxable profits up to £50,000. The main rate is 25% on profits above £250,000. Between £50,000 and £250,000 profits are tapered via HMRC's marginal relief fraction of 3/200, producing effective rates between 19% and 25%.

How do associated companies affect the thresholds?

Both the £50,000 lower limit and the £250,000 upper limit are divided by the number of associated companies plus one. So a company with 3 associated companies has a lower limit of £12,500 and an upper limit of £62,500 — the marginal band shrinks and the main rate applies much sooner.

What counts as an associated company for HMRC?

A company is associated with another if one controls the other, or both are under common control. Control means holding more than 50% of the share capital, voting rights or income distribution rights. Non-trading holding companies and dormant companies are typically excluded.

Does this calculator include R&D relief or capital allowances?

No. This tool applies headline HMRC rates only. Real-life liability changes materially with R&D tax credits (up to 27%–33% effective benefit for SME-scheme claimants), Annual Investment Allowance, Full Expensing, patent box, group relief and loss carry-back / carry-forward. Speak to a NovaLedge advisor for a real number.

When is UK Corporation Tax due?

For companies with taxable profits up to £1.5m, tax is due 9 months and 1 day after the end of the accounting period. Larger companies pay in quarterly instalments (QIPs) starting in month 7 of the accounting period. The CT600 return is due within 12 months of the accounting-period end.