A company tax calculator for the UK is only useful if it works the whole sum, and most do not. The corporation tax on the profit is the easy half; the hard half is that the profit depends on the director's salary, the salary carries employer's National Insurance that is itself deductible, and the dividend paid out of the after-tax profit is taxed on the director at a rate that depends on the band the dividend lands in. A limited company calculator that stops at corporation tax leaves out the larger part of the bill. This page sets out what the free ltd company tax calculator on this site works and in what order, which inputs move the answer, where it is an estimate, and the worked example the sheet starts from, so a director can judge any tax calculator limited company sites offer on the same test.
The order the sum has to run in
Turnover less allowable expenses gives the profit before the director's pay. The salary and the employer's National Insurance above the £5,000 secondary threshold at 15 percent, per gov.uk, come off next, because both are deductible. Corporation tax is worked on what is left, at 19 percent, 25 percent or the main rate less marginal relief, per gov.uk. The after-tax profit is what can be declared as dividend, and dividend tax is worked on the dividend above the £500 allowance at 10.75, 35.75 or 39.35 percent for the band. The director keeps the salary less income tax plus the dividend less dividend tax. Reverse any two steps and the answer is wrong.
The inputs that move the answer
The salary, because it changes three lines at once: the employer's NI, the corporation tax and the income tax. The corporation tax band, because the marginal band carries a 26.5 percent marginal rate that makes the salary decision different from the small profits band. The director's income tax band for the dividend, because a dividend that crosses into the higher band jumps from 10.75 percent to 35.75 percent. And the share of after-tax profit taken as dividend, because profit left in the company or paid into a pension is not taxed on the director at all. The uk company tax calculator on this site exposes each as a field.
Where any calculator is an estimate
A dividend that straddles two bands is taxed at both rates, and a calculator applying one rate to the whole is an estimate; the personal allowance is tapered above £100,000 of income, and Scottish bands apply to a Scottish director's salary; a short accounting period or an associated company cuts the corporation tax limits; and rates change on 1 April and 6 April. The limited company tax calculator uk directors reach for is a forecast for a decision, and the return prepared for the period is the answer; the calculator's fields take the current gov.uk figures as defaults so a changed rate can be typed in.
The worked example
Turnover £90,000, expenses £12,000, salary £12,570, marginal band, all after-tax profit as dividend, basic rate director, 2026 to 2027 rates: employer's NI £1,135.50; taxable profit £64,294.50; corporation tax £13,288.03 after £2,785.58 of marginal relief; dividend £51,006.47; dividend tax £5,429.45; income tax on salary nil; total tax and NI £19,852.98; the director keeps £58,147.02. Every figure on the free ltd company tax calculator recomputes as any input changes, and Dividvo Pro keeps each computation against the company and the year.
Questions people ask about company tax calculator
Is there an official HMRC company tax calculator?
HMRC publishes a marginal relief calculator for corporation tax and guidance on the rates, but not a calculator that combines corporation tax with the director's salary and dividend tax. The combined sum is what this site's calculator works, using HMRC's published rates.
Does the calculator work for a company with two directors?
Run it per director with their own salary and band, since each director has their own allowances and band, and add the corporation tax once. Dividvo Pro keeps a computation per shareholder and totals them.
What about VAT?
VAT is not in the sum. A registered company's turnover and costs are stated net of VAT, and VAT is neither its income nor its cost, so the calculator takes net figures. The VAT threshold and registration pages on this site cover VAT on its own terms.