Understanding Corporation Tax

Understanding Corporation Tax: What Every Business Owner Should Know

Corporation tax is a fundamental aspect of running a business in the UK. Understanding how it’s calculated, who needs to pay it, and the relevant deadlines and deductions can help you manage your business’s finances more effectively. In this blog post, we will provide a comprehensive guide on corporation tax to ensure you’re well-informed and prepared to meet your obligations.

What is Corporation Tax and Who Needs to Pay It?

Corporation tax is a tax on the profits of limited companies and some other organizations, including clubs, societies, associations, and cooperatives. If your business is incorporated, you are liable to pay corporation tax on:

  • Profits from trading activities: This includes income from sales and services.
  • Investments: Any profits from investments, such as interest on bank deposits or dividends.
  • Chargeable gains: Profits from selling assets, such as property or shares, for more than they cost.

Rates and Thresholds

The corporation tax rate in the UK is currently 25% for most companies. However, there are nuances based on the level of your profits:

  • Small Profits Rate: For companies with profits up to £50,000, the rate is 19%.
  • Main Rate: Companies with profits above £250,000 are taxed at 25%.
  • Marginal Relief: Companies with profits between £50,000 and £250,000 are eligible for Marginal Relief, which provides a gradual increase in the corporation tax rate from 19% to 25%.

Allowable Expenses and Deductions

To calculate your corporation tax, you can deduct allowable business expenses from your total income to determine your taxable profits. These expenses must be wholly and exclusively for business purposes. Common allowable expenses include:

  • Staff wages and salaries: Including employer National Insurance contributions.
  • Office expenses: Such as rent, utilities, and office supplies.
  • Travel and subsistence: Costs of business travel and accommodation.
  • Marketing and advertising: Costs related to promoting your business.
  • Professional fees: Fees paid to accountants, lawyers, and other professionals.
  • Depreciation of assets: Through capital allowances, which allow you to write off the cost of certain assets.

Filing Deadlines and Penalties for Non-Compliance

Staying compliant with corporation tax obligations involves meeting key deadlines:

  • Corporation Tax Return (CT600): You must file your corporation tax return 12 months after the end of your accounting period. This return details your taxable profits and the amount of corporation tax payable.
  • Tax Payment: Corporation tax must be paid 9 months and 1 day after the end of your accounting period. For example, if your accounting period ends on March 31, your tax is due by January 1 of the following year.

Penalties for Late Filing and Payment:

  • Late Filing Penalties: If you miss the filing deadline, penalties start at £100 and increase with further delays. Continued non-compliance can result in additional fines and interest on the overdue tax.
  • Late Payment Penalties: Interest is charged on any corporation tax paid late. The current rate can be found on the HMRC website. Prompt payment ensures you avoid these additional costs.


Understanding and managing corporation tax is essential for maintaining the financial health of your business. By staying informed about rates, allowable expenses, and filing deadlines, you can ensure compliance and optimize your tax position. At Merranti Accounting, we specialize in helping businesses navigate the complexities of corporation tax. Our team of experts is here to provide tailored advice and support to meet your specific needs.

If you have any questions about corporation tax or need assistance with your tax returns, contact Merranti Accounting today. We’re here to help you every step of the way, ensuring your business remains compliant and financially sound.

For more insights and personalized advice, reach out to our team of experts. We’re here to help you every step of the way.