Corporation tax estimate (with marginal relief)

How to use it

Enter your figures above — the result updates instantly and nothing leaves your browser. Results are illustrative, not a quote, tax computation or credit decision.

How to interpret the result

The output is a working estimate, not a filed liability. Corporation tax is ultimately assessed on your company's full tax computation — after capital allowances, R&D relief, group relief and other adjustments — so treat the figure here as a planning reference rather than the number to put in a board pack or send to HMRC.

Where a company's profit sits close to either threshold, small movements in profit — bringing forward a purchase, deferring income, or a one-off gain — can shift which rate band applies. If your figure lands near the boundary, it's worth re-running the estimate under a couple of realistic scenarios rather than relying on a single snapshot.

Limitations and good practice

The estimate assumes a single company. Where a business has associated companies, the rate thresholds are divided between them, which can pull a group's effective position into a higher band than a standalone estimate would suggest — a common surprise for owners restructuring into holding-company structures.

Because the calculation depends on assumptions about associated companies, accounting period length and reliefs claimed, it should sit alongside — not instead of — a proper computation from your accountant before you rely on it for cashflow planning, dividend decisions, or a funding application. Lenders assessing a company's position will typically expect to see the actual computation rather than an online estimate, so keep this tool for early-stage planning and quick sense-checks. See break-even with loan repayment for how a funding decision interacts with your wider cost base once tax is accounted for.