How Much Is Corporation Tax in the UK for 2026? A Detailed Guide for Business Owners

Running a limited company in the UK means keeping one eye on growth and the other on tax obligations. Among those obligations, corporation tax often causes the most confusion for small and medium business owners. Many still assume the rate is a simple flat percentage. In reality, the UK system now works with multiple thresholds and a marginal relief mechanism that affects thousands of growing companies.

So the real question is not only how much corporation tax a company pays, but also how the amount is calculated and when it must be paid. Understanding these details helps business owners avoid penalties, plan their cash flow, and make smarter financial decisions.

Corporation Tax Rates in the UK for 2026

As of 2026, the UK corporation tax system introduced by the government in April 2023 remains in place. The structure is based on profit levels.

Small Profits Rate: 19%

Companies with taxable profits of £50,000 or less pay corporation tax at 19 percent. This lower rate is designed to support smaller companies and startups that are still stabilising their finances.

Main Corporation Tax Rate: 25%

Companies generating profits above £250,000 pay the main corporation tax rate of 25 percent.

Marginal Relief Band

If your company earns between £50,000 and £250,000, the tax system applies marginal relief corporation tax. This gradually increases the tax rate between 19 percent and 25 percent instead of applying a sudden jump.

These thresholds are reduced if your company has associated companies. For example, if a business has one associated company, the thresholds may effectively be halved.

Corporation Tax Calculation UK: Understanding Taxable Profits

Corporation tax is charged on taxable profits, not on total revenue. This distinction is critical for accurate corporation tax calculation UK.

Taxable profits typically include:

• Trading profits from business activities

• Investment income such as interest

• Chargeable gains from selling company assets

• Profits from overseas branches if applicable

From this total, companies deduct allowable business expenses. These can include:

• Staff salaries and employer National Insurance contributions

• Office rent or workspace costs

• Marketing and advertising expenses

• Professional fees such as accountants or legal advisors

• Equipment purchases through capital allowances

For example, if a company generates £180,000 in total revenue and has £60,000 in allowable expenses, the taxable profit becomes £120,000. Because this sits within the marginal band, marginal relief would apply before determining the final tax amount.

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What Is Marginal Relief and Why It Matters

The marginal relief corporation tax mechanism ensures companies do not face a steep tax increase when profits slightly exceed £50,000.

The official HMRC formula used for marginal relief is:

Marginal Relief = (Upper limit − Profits) × 3 ÷ 200

Where the upper limit refers to £250,000.

This formula reduces the tax liability for companies whose profits fall between the two thresholds. While many businesses rely on accounting software or accountants to apply the calculation, understanding the concept helps directors forecast their tax bills more accurately.

For a company earning £100,000 in taxable profits, the effective tax rate may be roughly 22 to 23 percent, depending on the exact calculation.

Corporation Tax Payment Deadline UK

Paying corporation tax on time is essential. HMRC sets strict rules for payment deadlines.

For most companies, the corporation tax payment deadline UK is 9 months and 1 day after the end of the accounting period.

Example:

If your company’s accounting period ends on 31 December 2026, the corporation tax payment must be made by 1 October 2027.

The corporation tax return itself, known as the CT600, must be filed within 12 months after the accounting period ends.

Although these deadlines seem far apart, many accountants advise companies to calculate their tax liability soon after the financial year closes.

How Pay Corporation Tax to HMRC

Corporation tax payments in the UK are completed digitally. Businesses typically make an online corporation tax payment directly to HMRC.

Common payment methods include:

• Bank transfer to the HMRC corporation tax bank account

• Faster Payments or CHAPS transfer

• Online banking using your company’s corporation tax reference number

• Corporate debit or credit card

Every company receives a 17 character Corporation Tax Unique Taxpayer Reference (UTR). This reference must be included when making a payment so HMRC can correctly allocate the funds.

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Corporation Tax Late Payment Penalty

Late corporation tax payments trigger immediate financial consequences.

If a payment is missed, interest begins accumulating from the day after the deadline. HMRC regularly updates interest rates based on the Bank of England base rate.

Repeated late payments can lead to additional penalties or enforcement actions. In serious cases, HMRC may pursue debt collection procedures.

To avoid such situations, many UK business owners maintain financial flexibility. Some rely on revolving facility credit, which allows them to access funds during short term cash flow gaps. Others explore best UK business loans or unsecured business loans when tax obligations coincide with seasonal revenue dips. Businesses dealing with VAT obligations sometimes turn to vat bridging loans to ensure all tax payments are handled on time.

Proper planning protects both your finances and your reputation with HMRC.

Final Thoughts

For UK businesses in 2026, corporation tax is no longer a simple flat rate. It operates on a tiered structure that considers profit levels and includes marginal relief for companies in the middle band.

Understanding how much corporation tax your company must pay allows you to budget accurately, avoid penalties, and make informed financial decisions. The key factors are knowing your taxable profits, applying the correct rate, and meeting the payment deadline set by HMRC.

Businesses that treat tax planning as part of their overall financial strategy often find themselves in a stronger position to grow, invest, and navigate economic uncertainty with confidence.

FAQs

• How much corporation tax do UK companies pay in 2026?

Companies with profits up to £50,000 pay 19 percent, while companies with profits above £250,000 pay 25 percent. Businesses between these levels receive marginal relief.

• What is the corporation tax payment deadline in the UK?

Corporation tax must generally be paid 9 months and 1 day after the end of the company’s accounting period.

• How is corporation tax calculated in the UK?

It is calculated by subtracting allowable expenses from total income to determine taxable profit, then applying the relevant corporation tax rate.

• How do companies make an online corporation tax payment?

Businesses typically pay through bank transfer, online banking, or card using the HMRC corporation tax reference number.

• What happens if corporation tax is paid late?

HMRC charges interest on overdue payments and may impose penalties for repeated late payments.