How to reduce corporation tax, properly.

The tax charge is an output. The inputs are how profit is measured, when costs and income fall, and how the business is structured. By the time an accounting period has closed, most of the meaningful decisions have already been taken, which is why corporation tax planning that happens in the weeks before a filing deadline rarely changes the number by much.

The rate itself is also not a single figure. A company sitting near the lower profit threshold, or one with associated companies, can pay an effective marginal rate well above what the headline suggests. Knowing which band the company will land in, before the year ends, is often worth more than any individual claim.

The first pass is unglamorous and usually the most productive. Allowable expenses that were never coded as such, costs sitting in the wrong period, expenditure treated as capital that qualifies for relief, and interest and finance costs that were never reviewed against the deductibility rules.

Capital allowances deserve their own look. Plant and machinery, integral features within a building, fixtures acquired as part of a property purchase, and expenditure that qualifies for the annual investment allowance or full expensing all reduce taxable profit in the year rather than over the life of the asset. Companies that have bought or fitted out property frequently under claim here, sometimes for years.

Timing matters as much as eligibility. Capital expenditure committed shortly before a year end can fall into a different period from the same spend a fortnight later, with the relief following it.

Research and development relief remains one of the largest reductions available to a trading company, and also the one most likely to be challenged. The test is whether the work sought an advance in science or technology and resolved genuine technical uncertainty, not whether the project felt innovative commercially.

The claims that hold up are the ones documented while the work happens: what the uncertainty was, who worked on it, why it was not readily deducible by a competent professional, and how the costs map to the activity. The claims that fail are assembled afterwards from a payroll report. If the company builds software, tooling or process technology in house, this is worth testing properly rather than dismissing.

Losses are an asset and can be wasted. Carrying a loss back against an earlier profitable period, carrying it forward, or surrendering it as group relief to another company in the group are different decisions with different cash outcomes, and the best one depends on the rate applying in each period rather than on the size of the loss.

The accounting date itself is a lever. Changing it moves income and expenditure between periods, which can matter around a large contract, a disposal, or a year where profits cross a rate threshold. Associated company counts, often overlooked in owner managed groups, can push companies into the marginal band without anyone deciding to.

Corporation tax cannot be looked at on its own where the shareholders are also the people running the business. Salary is deductible and carries national insurance. Dividends are not deductible and are taxed personally. Employer pension contributions are usually deductible in the period paid where they are wholly and exclusively for the trade.

The right mix depends on the owner's wider position, including other income, longer term plans for the company, and whether a sale is in view. Optimising the company charge in isolation can quietly increase the total tax paid across company and shareholder together.

Where a business trades across borders, structure starts to dominate. How companies within a group charge each other, where intellectual property sits, where profit is recognised and where people actually work all shape the outcome, and all sit under transfer pricing rules that expect intra group pricing to reflect what independent parties would agree.

An overseas company only changes the answer where the substance is real. Residence follows central management and control, so a company managed from the UK remains taxable here whatever the registered office says, and activity abroad can create a taxable presence in that country. Our briefing on substance covers what has to be true in practice, and our note on UK exit tax covers the charge that arrives if the company leaves.

Three patterns account for most of the trouble. Claims without contemporaneous evidence, where the position may well be right but cannot be shown. Arrangements with no commercial purpose beyond the tax result, which anti avoidance rules are built to catch. And positions that were never written down, so nobody can reconstruct the reasoning when a question arrives two years later.

A reduction is only worth having if it survives scrutiny with interest and penalties left on the table. That standard, rather than the size of the saving, is what we design to.

We start with the numbers as filed and the structure as it stands, then test them against the reliefs available, the periods in play, and the shape the business is actually taking over the next few years. Where a position needs support, we put it in writing before it is needed rather than after it is questioned.

Tax efficiency is one of three parts of our tax advisory practice, alongside planning and technical consultancy. If a cross border move is part of the picture, it belongs in the same conversation as business relocation, not after it.