The UK Corporation Tax Marginal Rate Trap: Why Profits Between £50k and £250k Are Taxed at 26.5%

From April 2023, UK Corporation Tax rates split: 19% for companies with profits up to £50,000, 25% for companies with profits over £250,000, and a 'marginal relief' taper for profits in between. Most discussion focuses on the headline rates, but the practical effect of the taper is that for every £1 of profit between £50,000 and £250,000, the effective marginal rate is 26.5% — higher than the stated 25% main rate. This surprises many directors and their advisers.

How marginal relief works. The taper reduces the difference between the full 25% charge and what would have been charged at 19%. The formula: the relief is 3/200 × (Upper Limit − Augmented Profits) × (Profits ÷ Augmented Profits). In plain terms: your company pays 25% on the whole profit, then gets a reduction that phases out as profits rise from £50,000 to £250,000. The effective rate at £50,000 is 19%, at £100,000 it is approximately 21.5%, at £150,000 approximately 23.25%, at £200,000 approximately 24.6%, and at £250,000 the full 25% applies.

Why this matters for Arab directors. The £50,000–£250,000 band is exactly where many consultancy, trading, and property companies operated by Gulf directors fall. A director who manages profits close to £50,000 by timing salary and dividend payments, pension contributions, and capital expenditure spends their accounting year on the right side of the taper. A director who lets profits build without planning can inadvertently pay 26.5% on the incremental profit rather than 19%.

Associated companies complicate the picture. The £50,000 and £250,000 thresholds are divided by the number of 'associated companies' — companies under common control (broadly, where one person or group controls more than 50% of each company). If you own two active UK companies, each threshold is halved: the 19% rate applies only up to £25,000 per company, and the full 25% kicks in above £125,000. Directors with both a trading company and a property company, or two trading companies, should be aware that the lower thresholds apply from day one of the second company.

Practical tax planning around the band. Tools for managing profits in the marginal relief band include: employer pension contributions (deductible before CT, removes profit from the band), timing of capital expenditure (Annual Investment Allowance), salary level decisions, and timing of dividend payments (dividends are not CT-deductible but affect the personal extraction decision). For companies regularly sitting in the £50,000–£250,000 range, the interaction of all these levers is worth modelling annually.