Corporation Tax Guide for UK Limited Companies (2025/26)
Corporation Tax is one of the primary taxes paid by limited companies in the United Kingdom. Understanding how it works is essential for directors who want to manage their business finances effectively and avoid unexpected liabilities. For the 2025/26 tax year, the UK continues to operate a tiered Corporation Tax system that applies different tax rates depending on company profit levels.
Currently, companies with profits of up to £50,000 are subject to the small profits rate of 19%. Companies with profits exceeding £250,000 pay the main rate of 25%. Businesses with profits between these thresholds benefit from marginal relief, which gradually increases the effective tax rate between the two bands. This structure is designed to prevent smaller companies from facing the full higher tax rate immediately as they grow.
An important factor when calculating Corporation Tax thresholds is whether a company has associated companies. Associated companies are businesses under common control. If multiple associated companies exist, the profit thresholds are divided between them. For example, if two companies are associated, the £50,000 and £250,000 thresholds are halved. This rule often catches business owners by surprise and can significantly increase the effective tax rate within group structures.
Corporation Tax is calculated based on taxable profits, which differ from accounting profits. Taxable profits typically include:
Trading profits from business activities
Investment income, such as interest
Chargeable gains from the sale of assets
However, companies are able to deduct allowable expenses before calculating their final tax liability. These expenses usually include costs that are incurred wholly and exclusively for the purpose of the business. Examples include wages, rent, professional fees, software subscriptions, and certain travel costs.
Companies can also claim capital allowances when purchasing certain assets used within the business. The Annual Investment Allowance (AIA) currently allows businesses to claim 100% tax relief on qualifying plant and machinery purchases up to £1 million per year. This can significantly reduce taxable profits when companies invest in equipment or technology.
Another key consideration for many owner-managed businesses is how profits are extracted. After Corporation Tax has been paid, directors may withdraw funds through salaries, dividends, or pension contributions. Each method has different tax implications, so planning these withdrawals carefully can improve overall tax efficiency.
Corporation Tax must usually be paid nine months and one day after the end of the company’s accounting period, while the Corporation Tax return must be filed within 12 months of the year end. Because the payment deadline occurs earlier than the filing deadline, companies should ensure they estimate their tax liability in advance to avoid cash flow pressure.
Proactive planning is essential. Reviewing financial performance before the end of the accounting period allows businesses to identify opportunities to claim reliefs, make pension contributions, or invest in assets that reduce taxable profit.
For many businesses, working closely with an accountant ensures that Corporation Tax obligations are managed efficiently while remaining fully compliant with HMRC rules