Corporation Tax Calculator (UK 2024)
After allowable deductions
UK Corporation Tax: 19% (profits <£50K) · Marginal relief (£50K–£250K) · 25% (profits >£250K)
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What is Corporation Tax Calculator?
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Corporation Tax is a cornerstone fiscal obligation for any UK-incorporated business, directly impacting net margins, reinvestment capacity, and shareholder distributions. Calculated on taxable profits—which encompass trading income, investment yields, and chargeable capital gains—this liability requires precise, proactive forecasting. For corporate treasury teams and business owners, miscalculating this figure or conflating book profit with taxable profit can trigger severe working capital deficits or unexpected HMRC penalties. The UK corporate tax landscape operates on a tiered structure rather than a flat-rate system. Under the current regime, companies with profits below the lower threshold benefit from the small profits rate of 19%, while those exceeding the upper threshold are taxed at the main rate of 25%. For businesses operating in the intermediate zone, a tapering mechanism known as Marginal Relief is applied to ensure a smooth transition, creating an effective marginal rate of 26.5% on profits within this bracket. These thresholds are subject to downward adjustments if a company has associated entities or operates under a short accounting period. This Corporation Tax Calculator serves as an essential decision-support tool for financial analysts, CFOs, and entrepreneurs. By translating complex HMRC rules into an immediate, reliable tax estimate, it enables organizations to run scenario analyses, optimize year-end capital expenditures, and make data-driven dividend declarations. It removes the guesswork from intermediate profit bands, allowing leadership to allocate cash reserves strategically ahead of formal tax filing.
Calkulon makes complex calculations simple — built for students and everyday problem-solvers.
Formulė
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The standard UK Corporation Tax calculation for the financial year starting 1 April 2026 is structured as follows: Tax = (Taxable Profits x 25%) - Marginal Relief. If profits are below the lower threshold (GBP 50,000 adjusted), Tax = Taxable Profits x 19%. If profits exceed the upper threshold (GBP 250,000 adjusted), Tax = Taxable Profits x 25%. For profits falling between these thresholds, Marginal Relief is calculated as: Marginal Relief = (Upper Limit - Augmented Profits) x (Taxable Profits / Augmented Profits) x (3/200). Where no exempt distributions exist, this simplifies to: Marginal Relief = (Upper Limit - Taxable Profits) x (3/200).Variable Legend
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| Symbol | Vardas | Vienetas | Aprašymas |
|---|---|---|---|
| TP | Taxable profits | — | The net profits subject to Corporation Tax after accounting for trading income, expenses, capital allowances, and tax reliefs. |
| UL | Upper limit | — | The upper profit threshold (normally GBP 250,000), adjusted proportionally for associated companies and the length of the accounting period. |
| AP | Augmented profits | — | The sum of taxable profits and any exempt distributions (such as dividends received from non-group companies). |
| MR | Marginal Relief | — | The financial relief deducted from the main rate tax liability to smooth the transition between the 19% and 25% rates. |
| 3/200 | Standard fraction | — | The statutory multiplier used to compute Marginal Relief for non-ring-fenced corporate profits. |
How to Corporation Tax Calculator
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- 1Input the company's adjusted taxable profits for the accounting period, ensuring non-deductible expenses like client entertainment are added back and capital allowances are deducted.
- 2Specify the number of associated companies under common control, which will systematically reduce the lower and upper tax thresholds.
- 3Define the length of the accounting period to allow the system to pro-rate the profit thresholds if the period is shorter than 12 months.
- 4The calculator automatically determines whether the company falls under the Small Profits Rate (19%), the Main Rate (25%), or the Marginal Relief transition band.
- 5For businesses in the transition band, the system applies the official HMRC fraction to calculate the exact Marginal Relief deduction.
- 6Review the final estimated tax liability, effective tax rate, and net after-tax income to inform corporate budgeting and quarterly cash allocations.
Worked Examples
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GBP 45,000 x 19% = GBP 8,550.
Because the taxable profits fall comfortably below the lower threshold of GBP 50,000, the company qualifies entirely for the Small Profits Rate of 19%. No Marginal Relief calculations or complex adjustments are required, making this a straightforward liability calculation.
Tax at 25% is GBP 30,000, less GBP 1,950 Marginal Relief.
With profits falling between the GBP 50,000 and GBP 250,000 thresholds, the company is subject to the main rate of 25% but receives Marginal Relief. The relief is calculated as (GBP 250,000 - GBP 120,000) x 3/200 = GBP 1,950, reducing the net tax bill and yielding an effective tax rate of 23.38%.
GBP 350,000 x 25% = GBP 87,500.
Since the taxable profits exceed the upper threshold of GBP 250,000, the entire profit amount is taxed at the flat main rate of 25%. Marginal Relief is no longer applicable once profits cross this upper limit.
Thresholds are halved to GBP 25,000 and GBP 125,000. Tax at 25% is GBP 20,000, less GBP 675 Marginal Relief.
Having one associated company halves the lower and upper thresholds to GBP 25,000 and GBP 125,000 respectively. Consequently, the profit of GBP 80,000 sits in the adjusted Marginal Relief band, resulting in a higher effective tax rate than if the company operated in isolation.
Thresholds pro-rated to GBP 25,000 and GBP 125,000. Net tax is GBP 15,000 minus GBP 1,425 Marginal Relief.
For an accounting period of only six months, the thresholds must be pro-rated by 50%. The lower limit becomes GBP 25,000 and the upper limit becomes GBP 125,000. The GBP 60,000 profit is taxed at 25% less Marginal Relief of (GBP 125,000 - GBP 60,000) x 3/200 = GBP 1,425.
Real-World Applications
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Corporate cash flow budgeting to ensure precise tax reserves are allocated monthly, preventing year-end liquidity constraints.
Strategic dividend planning by calculating accurate after-tax profits available for distribution to shareholders.
Capital expenditure modeling to evaluate how investment in machinery or technology reduces taxable profit via Capital Allowances.
Pre-acquisition financial due diligence to estimate the tax liabilities and effective tax rates of target corporate entities.
Special Cases
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Associated companies
When a business operates under a group structure or shares common control with other entities, the statutory lower and upper profit thresholds must be divided by the total number of associated companies plus one. This preventing companies from artificially splitting profits across multiple entities to exploit the lower 19% tax bracket.
Short accounting periods
When an accounting period is less than a full 12-month calendar year, the profit thresholds must be pro-rated based on the number of days in the active period. This adjustment ensures that companies changing their accounting dates or winding up operations do not receive an unfair threshold advantage.
Periods spanning 31 March
When a company's financial year straddles a date where tax rates or rules change (such as a change in the main rate or marginal relief fraction on 1 April), the profits must be split chronologically. Profits are typically apportioned on a daily basis to apply the respective rates of each financial year correctly.
UK Corporation Tax Reference for Financial Year Starting 1 April 2026
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| Profit band or item | Rate or threshold | Notes |
|---|---|---|
| Small profits rate | 19% | Applicable to companies with adjusted profits up to the lower threshold |
| Main rate | 25% | Applicable to companies with adjusted profits exceeding the upper threshold |
| Lower threshold | GBP 50,000 | Must be divided by the number of associated companies plus one, and pro-rated for short periods |
| Upper threshold | GBP 250,000 | Must be divided by the number of associated companies plus one, and pro-rated for short periods |
| Marginal Relief fraction | 3/200 | The fraction used to calculate tax relief for profits within the transition band |
Frequently Asked Questions
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How do associated companies affect my Corporation Tax thresholds?
When companies are under common control, they are considered associated for tax purposes. This relationship requires the lower and upper profit thresholds (GBP 50,000 and GBP 250,000) to be divided equally among all associated entities plus the claiming company. Consequently, a group of three associated companies will see their individual upper thresholds reduced to GBP 83,333, pushing them into the 25% tax bracket at much lower profit levels.
Why is there a difference between my accounting profit and taxable profit?
Accounting profit is calculated using standard accounting principles (like GAAP or IFRS) to show commercial performance, whereas taxable profit is dictated by statutory tax laws. Certain commercial expenses, such as client entertainment and depreciation, are not tax-deductible and must be added back. Conversely, statutory deductions like Capital Allowances or research and development incentives are subtracted to arrive at the final taxable profit figure.
What is the effective marginal tax rate within the Marginal Relief band?
For profits between GBP 50,000 and GBP 250,000, the effective tax rate on each additional pound of profit is actually 26.5%. This occurs because of the mathematical mechanics of the Marginal Relief formula, which gradually claws back the benefit of the lower 19% rate until the flat 25% main rate is reached. Understanding this high marginal rate is critical when timing business expenditures or bonuses.
How do short accounting periods impact my company's tax calculation?
If your company's accounting period is shorter than 12 months—which often happens in the first year of trading or during a change of year-end—the profit thresholds must be time-apportioned. For example, a 3-month accounting period reduces the lower threshold to GBP 12,500 and the upper threshold to GBP 62,500. This ensures that the tax rates are applied fairly relative to the active trading duration.
How can I utilize this calculator for quarterly cash flow forecasting?
By inputting your year-to-date taxable profits and run-rate projections, you can estimate your total annual tax liability well in advance. This allows corporate treasurers to set aside accurate monthly or quarterly tax reserves, preventing working capital shortages when the payment deadline arrives. It also helps determine whether the company will trigger the quarterly installment payment (QIPs) regime for larger entities.
What are augmented profits and why do they matter for Marginal Relief?
Augmented profits are your company's taxable profits plus any exempt distributions received, such as dividends from non-group companies. While these dividends themselves are not subject to Corporation Tax, they are included in the calculation to determine where your company sits relative to the lower and upper thresholds. High augmented profits can reduce or entirely eliminate the Marginal Relief you can claim on your taxable trading profits.
Can I offset previous years' trading losses using this calculator?
Yes, trading losses brought forward from previous years should be deducted from your trading profits before entering the final figure into the calculator. Reducing your taxable profit figure directly lowers your position relative to the tax thresholds, potentially moving your business from the main rate or marginal band down to the small profits rate.
Common Mistakes to Avoid
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- !Using standard EBITDA or net book profit instead of adjusted taxable profit, which fails to account for non-deductible expenses or capital allowances.
- !Failing to declare associated companies, which artificially inflates the profit thresholds and leads to an underestimation of the tax liability.
- !Neglecting to pro-rate profit thresholds for short accounting periods, resulting in incorrect tax rate applications.
- !Overlooking augmented profits from non-group dividends, which can inadvertently reduce or disqualify the company from receiving Marginal Relief.
Pro Tip
To optimize your corporate tax position, calculate your estimated liability using adjusted taxable profits rather than book profits. Accelerating qualifying capital expenditures before your year-end under the Annual Investment Allowance (AIA) can lower your taxable profit, potentially pushing your business into a lower tax bracket or maximizing your Marginal Relief.
Did you know?
The UK's highest historic corporate tax rate reached a staggering 52% in the late 1970s and early 1980s. The introduction of the tiered system with Marginal Relief in modern tax years represents an effort to keep the UK competitive globally while protecting small business cash flows.
References
Read the full guide on how to use this calculator effectively
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