You're probably looking at this year's company profit, wondering one thing: how much Corporation Tax will I pay?
Fair question. Most directors don't struggle with the idea of tax. They struggle with the moving parts. One rate applies at one profit level, another applies higher up, and the middle band confuses almost everyone. Then there's the nasty surprise many directors miss completely: owning more than one company can shrink your thresholds and push you into a higher rate earlier than expected.
If you run a UK limited company, the answer isn't just “19% or 25%”. It depends on your taxable profit, whether marginal relief applies, and whether the associated companies rules are reducing your limits. Get those wrong and your estimate is wrong.
Understanding the 2026 Corporation Tax Rates
The 2026 position is simple at headline level. The calculation underneath isn't.
For the financial year beginning 1 April 2026, the main UK Corporation Tax rate is 25% for limited companies with taxable profits exceeding £250,000, while a small profits rate of 19% applies to companies with profits of £50,000 or less, according to the official Corporation Tax rates and allowances publication.
The three bands that matter
There are three practical zones for most limited companies.
| Profit position | What applies | What it means |
|---|---|---|
| Up to £50,000 | Small profits rate | You pay 19% |
| £50,001 to £250,000 | Marginal relief | You don't jump straight to a flat 25% |
| Above £250,000 | Main rate | You pay 25% |
That middle band is where directors make bad assumptions. They see “main rate 25%” and think every pound above £50,000 gets taxed that way. It doesn't.
Why the middle band exists
HMRC doesn't want a cliff edge. If your company moved from just below £50,000 to just above it, a sudden leap to the full main rate would be clumsy and unfair. So the system uses marginal relief to taper the tax burden upward.
In plain English, your tax bill rises gradually between the lower and upper limits. That's the part many directors never model properly when they ask, How much Corporation Tax will I pay?
Practical rule: If your profits sit somewhere in the middle band, don't estimate tax by multiplying profit by 25%. That shortcut is wrong.
If you want a broader primer on the headline rates before getting tactical, this guide on the Corporation Tax rate is worth a look.
The strategic point
The rate itself is only step one. Your real job as a director is to know which band you're in after proper tax adjustments, not after a rough glance at your bookkeeping software.
That's why good tax planning starts with taxable profit, not turnover, and not your accounting profit before adjustments.
How to Determine Your Company's Taxable Profit
You finish the year thinking profit is £90,000, so you budget tax on that figure. Then your accountant strips out disallowable spend, adjusts for allowances, checks investment income, and the number that drives Corporation Tax is very different. That gap is where directors misprice tax, overdraw cash, and get caught out by the associated companies trap.
Start with the tax computation, not your draft accounts.
Use the right order
A clean calculation usually follows four steps:
- Add up taxable income from trading, investments, and chargeable gains.
- Deduct allowable business expenses that meet the tax rules.
- Claim available reliefs and allowances such as capital allowances, trading losses, or Patent Box where relevant.
- Check whether marginal relief applies based on your profit position.
If you want a plain-English explanation of how the lower rate and relief rules fit together, see this guide to the small profits rate and marginal relief rules.
The adjustments that usually make the biggest difference
Bookkeeping profit and taxable profit are rarely identical. The expensive mistakes are usually basic.
Costs that often reduce taxable profit include:
- Salaries and wages paid for genuine work
- Employer pension contributions made and recorded properly
- Qualifying business travel
- Home office costs where there is a real business basis
- Capital allowances on qualifying equipment and assets
Then come the add-backs. These are the items directors keep trying to squeeze through and HMRC keeps rejecting:
- Client entertaining
- Personal spend put through the company
- Mixed-use costs with no proper business-private split
- Fines and penalties
- Depreciation, which is an accounting charge, not a tax deduction
Get these wrong and your tax estimate is nonsense.
Do not confuse taxable total profits with augmented profits
The distinction catches out experienced directors, not just new ones. Taxable total profits are used to work out the core liability. Augmented profits are used for rate thresholds and marginal relief, and they can include distributions such as franked investment income.
That point gets sharper if you own more than one company. The lower and upper profit limits are split between associated companies. So a director with several entities can drift into a higher effective tax band far earlier than expected, even where each company looks modest in isolation.
This is the trap. Directors look at one company's bookkeeping profit, ignore the group picture, and assume they still sit comfortably in the lower band.
What to do in practice
Review your year-end profit with a tax lens before you decide dividends, bonuses, pension timing, or asset purchases. Check disallowable costs. Check allowances. Check investment income. Then check how many associated companies you have, because that can shrink your thresholds and change the answer fast.
Good tax planning starts here. If the taxable profit figure is wrong, every decision after that is built on sand.
Navigating the Marginal Relief Calculation
A lot of directors get caught here after a profitable year. They assume corporation tax jumps cleanly from 19% to 25%, then discover the answer sits in the middle and gets worse again if they own other companies.
Marginal relief softens the move from the small profits rate to the main rate. If your company falls between the lower and upper limits, you do not pay 25% on the whole profit. You get relief that reduces the bill, but that relief shrinks as profits rise.
The part many directors miss is the associated companies trap. If you control multiple companies, the profit thresholds are split. That can push a company into the marginal relief band, or straight out of it, much earlier than expected. If you need the threshold rules set out clearly, see this guide to the small profits rate and marginal relief thresholds.
What the formula is really doing
The statutory formula matters if you are calculating the liability properly rather than relying on a rough estimate:
Tax = (25% × Taxable Profits) – [3/200 × (£250,000 – Augmented Profits)] × (Taxable Profits / Augmented Profits)
The point is simple. Relief is deducted from the main rate calculation, and the deduction gets smaller as augmented profits rise through the band.
That is why directors often describe the middle band as feeling steeper than expected. The company is not taxed at one flat middle rate. It is moving from the small profits position toward the main rate, with relief tapering away as profit increases.
What this means in practice
Treat the marginal relief band like a sliding scale.
Below the lower limit, the small profits rate applies. Above the upper limit, the main rate applies. Between those points, timing decisions can change the bill in a meaningful way. Pension contributions, capital expenditure, group profit allocation, and year-end timing all deserve a proper review before the accounts are finalised.
This is also where weak planning shows up fast. A director looks at one company in isolation, ignores the other entities under common control, and uses the full thresholds anyway. The estimate looks fine on paper. The tax bill does not.
Here's a walkthrough that helps visual learners.
Where directors go wrong
The recurring mistakes are:
- Using accounting profit instead of the tax-adjusted figure
- Ignoring augmented profits in the relief calculation
- Applying 25% to the whole profit when the company sits in the middle band
- Missing the fact that associated companies reduce the thresholds
The first three errors produce a bad calculation. The fourth changes the tax band itself, which is why it is usually the costliest mistake. If you run more than one company, check the association position before you estimate corporation tax. Do not leave that until the return is being prepared.
Corporation Tax Calculation Worked Examples
Abstract rules are fine. Numbers are better.
The table below shows three common profit positions and how the tax treatment changes. These examples assume the standard thresholds apply and no associated companies adjustment is needed.
Corporation Tax calculation examples for 2026
| Metric | Example 1 | Example 2 | Example 3 |
|---|---|---|---|
| Profit | £40,000 | £100,000 | £300,000 |
| Relevant band | Small profits rate | Marginal relief band | Main rate |
| Headline rule | Profit at or below lower limit | Profit between lower and upper limits | Profit above upper limit |
| Tax treatment | 19% applies | Marginal relief applies, so it is not a flat 25% on the whole amount | 25% applies |
| Basic calculation approach | Multiply taxable profit by 19% | Apply the marginal relief formula | Multiply taxable profit by 25% |
| Effective position | Small profits rate applies in full | Lower effective average rate than the headline 25% | Main rate applies in full |
Example 1 at £40,000
This one is straightforward. If your company's taxable profit is £40,000, it sits within the small profits band, so the 19% rate applies.
There's no marginal relief issue here. Your planning focus is usually on making sure the taxable profit figure is correct and that you haven't missed legitimate deductions.
Example 2 at £100,000
Many directors make errors in their estimates. A company with £100,000 in profit does not pay 25% on the full amount.
That point is made clearly in this explanation of what tax a limited company pays, which notes that a limited company earning £100,000 in profit will benefit from the marginal relief calculation, resulting in a lower effective average rate than the headline 25%. The same source explains that profits between £50,000 and £250,000 fall within a marginal relief mechanism that creates a sliding marginal tax effect of 26.5% within that band.
A £100,000 profit figure sits in the awkward middle. That's exactly where rough estimates go wrong and year-end planning becomes valuable.
Example 3 at £300,000
At £300,000, the company is above the upper threshold. The main rate applies, so the tax calculation is much cleaner. You don't get marginal relief once profits are over the upper limit.
At that level, the conversation usually shifts away from “what rate applies?” and toward “have I structured the company, costs and extraction strategy sensibly?”
Key Rules and Strategic Tax Planning
Most directors focus on rates. Sharp directors focus on structure.
A company can have perfectly good profits and still overpay tax because the director ignored one ugly rule, claimed expenses lazily, or left planning until after the year end. The biggest trap by far is the associated companies rule.
The associated companies trap
If you own or control multiple companies, you can't assume each one gets the full £50,000 and £250,000 thresholds.
As explained in Ross Martin's company tax rates guidance, a frequent strategic pitfall is ignoring the associated companies rule, which divides the £50,000 and £250,000 thresholds by the number of active group companies worldwide. That can cause firms with 2 subsidiaries to lose marginal relief eligibility at just £125,000 profit instead of £250,000.
That's a brutal surprise if you've set up separate companies for contracts, property, consulting, or side ventures.
What division of thresholds looks like
The principle is simple. More associated companies means smaller thresholds per company.
This summary of UK corporate income tax rules states that if a company has associated companies, both the £50,000 lower limit and the £250,000 upper limit are divided by the total number of active associated companies worldwide. It gives the example of a group of three companies, where the individual thresholds become £16,667 and £83,333.
That changes your planning completely. A profit level that looked comfortably inside one band can land in a very different place once the thresholds are split.
Owning more companies doesn't automatically save tax. Sometimes it does the opposite because the tax bands shrink faster than the commercial benefit grows.
Practical planning moves that actually matter
If you want a cleaner Corporation Tax outcome, focus on decisions that move the taxable profit figure legally and deliberately.
- Review expenses before year end. Don't wait until the accounts are drafted. Check that business travel, software, subscriptions, pension contributions and other valid costs have been captured properly.
- Use employer pension contributions thoughtfully. For many directors, company pension funding is one of the cleaner ways to reduce taxable profit while moving money into long-term value.
- Think about timing. If profits are close to a threshold, the timing of invoices, bonuses, pension contributions or capital spending can affect the final result.
- Check your company structure. If you've created multiple entities over time, don't assume they're tax-neutral. They may be shrinking your thresholds and pushing tax up.
Don't miss the deadlines
Planning is pointless if you then miss the compliance basics.
The Corporation Tax payment deadline is 9 months and 1 day after the end of the accounting period, while the Company Tax Return filing deadline is 12 months after the period ends, as explained in this guide on Corporation Tax deadlines and ring-fence profits.
Those are separate deadlines. Payment comes first. Directors often remember the filing date and forget the money was due earlier.
One blunt recommendation
If you have more than one company, stop using generic online tax estimates.
Those calculators usually assume the standard thresholds. If the associated companies rules apply, the estimate can be miles off. That's how directors drift into bad decisions on dividends, pension timing and profit extraction.
Optimising Your Tax Position
If you're still asking, how much Corporation Tax will I pay, the honest answer is this: you'll pay whatever falls out of the correct profit figure, the correct band, and the correct company structure.
That's why optimisation starts with accuracy. Get the taxable profit right. Check whether marginal relief applies. Then test whether associated companies change the thresholds before you make extraction decisions.
The directors who manage this well don't treat Corporation Tax as a once-a-year admin job. They treat it as part of running the business properly. They review expenses early, use pension contributions with intent, and avoid sleepwalking into structural mistakes that raise tax for no good reason.
If your setup is simple, you can get a solid estimate with disciplined records and a proper calculation. If your profits are rising, your company structure is more complex, or you run more than one entity, a strategic review usually pays for itself in clarity alone.
For a practical next step, read this guide on how to reduce Corporation Tax in the UK.
Tax Compass helps UK limited company directors make sense of Corporation Tax, profit extraction and tax planning without the usual jargon. If you want a clearer view of what your company should be paying, and where you may be overpaying, visit Tax Compass.