Corporation tax

Introduction to Corporation Tax for Start-ups

For start-ups, understanding Corporation Tax is a crucial aspect of setting a strong financial foundation. Limited businesses must comply with this tax obligation. Comprehending the intricacies of Corporation Tax can indeed play a significant role in establishing a new business.

Registering Your Start-up for Corporation Tax

After setting up your company, it is mandatory to register with HM Revenue and Customs (HMRC) for Corporation Tax. The deadline for this registration is three months from the day your business starts trading or becomes active. Any delay can lead to penalties. The registration process is conducted online on the HMRC website, which issues a Unique Taxpayer Reference (UTR) for your company.

Navigating Changes in Corporation Tax Rates

The UK’s Corporation Tax has undergone recent modifications, shifting from a standard 19% rate applicable to all companies. Starting April 2023, the flat rate is no longer in place, introducing a layered system.

Businesses with an annual income of £50,000 or less will continue to pay at the previous rate of 19%, thanks to the Small Business Rate Relief. However, companies earning above £250,000 annually will now face a 25% tax rate.

For those companies earning between £50,000 and £250,000, a graduated or tapered rate applies, making the tax situation a tad more complex. Businesses in this range are eligible for Marginal Small Companies Relief (MSCR). This relief uses a formula that applies a 26.5% marginal relief rate to calculate a final effective tax rate based on a company’s profits.

Understanding Accounting Periods and Deadlines

The Corporation Tax accounting period typically spans 12 months, aligning with your company’s financial year. You are obligated to file your company tax return (CT600) and pay your Corporation Tax bill within nine months and one day post your accounting period. Keeping accurate financial records is paramount for calculating your company’s profits and tax liabilities accurately.

Availing Reliefs and Allowances

Start-ups in the UK can benefit from several tax reliefs and allowances offered by the Government. Some notable ones include:

  • Research and Development (R&D) Tax Credits: Start-ups involved in qualifying R&D projects may be eligible for these credits, allowing them to claim a larger proportion of their R&D expenditure against their Corporation Tax bill.
  • Capital Allowances: When your company purchases assets like equipment or machinery, you may claim capital allowances to deduct the cost of these assets from your taxable profits.
  • Patent Box: If your start-up owns a qualifying patent, you can apply for Patent Box relief, which allows you to pay a reduced Corporation Tax rate on profits earned from patented inventions.

These are just a few of the many tax reliefs available to your start-up.


In conclusion, having a comprehensive understanding of Corporation Tax is indispensable for running a successful start-up in the UK. Prompt registration, being aware of tax rates and deadlines, and leveraging reliefs and allowances can put your start-up in an excellent position to thrive. For any additional advice on Corporation Tax for your start-up, feel free to reach out to us at