Corporation Tax Calculator (UK 2024)
Calculate UK Corporation Tax on company profits. Applies the small profits rate (19%), main rate (25%), and marginal relief calculation.
Corporation Tax Guide 2026/27
Three-Tier System (Since April 2023)
Profits up to £50,000: 19% (small profits rate). Profits £50,001 to £250,000: marginal relief — effective rate gradually increases from 19% to 25%. Profits over £250,000: 25% flat rate. The marginal relief formula: (£250,000 − profit) × (profit / profit) × 3/200. This creates a smooth transition without a 'cliff edge' at £50,000. Effective rates within marginal band: £75,000 profit: ~22% effective. £100,000: ~23%. £150,000: ~23.7%. £200,000: ~24.4%. £250,000: 25%. Important: thresholds DIVIDE by
Associated Companies Rule
Companies are 'associated' if: one controls the other, or the same person/group controls both. Includes: parent and subsidiaries. Companies under common ownership. Companies linked through family relationships in some cases. Impact: thresholds divided by number of associated companies. Example: holding company plus 4 trading subsidiaries = 5 associated. Lower threshold per company: £50,000 / 5 = £10,000. Upper threshold: £250,000 / 5 = £50,000. Each company hits marginal relief and main rate at
What Counts as Taxable Profit
Start with accounting profit. Adjustments to arrive at taxable profit: ADD: depreciation (not allowable). Capital allowances claimed elsewhere. Disallowable expenses (entertainment except staff, fines, etc.). DEDUCT: capital allowances (instead of depreciation — typically more generous). Loss relief. R&D enhanced deductions (SME scheme: 86% additional deduction since April 2023). Patent Box rate: 10% on qualifying patent income. Capital allowances 2026/27: full expensing of qualifying plant and
R&D Tax Credits
R&D tax credit scheme: significant relief for innovating companies. SME scheme (from April 2023): qualifying R&D expenditure gets 86% additional deduction (so total deduction = 186% of cost). For loss-making SMEs: surrender losses for cash credit (10% from April 2023). RDEC scheme (large companies and some SMEs): 20% taxable credit. Qualifying activities: scientific or technological advance. Must seek to resolve scientific or technological uncertainty. Software development qualifies if creating
Recommended for this calculator