Check Your Corporation Tax Deadlines

Missing corporation tax deadlines can lead to costly penalties and unnecessary stress. Many companies struggle to keep track of their tax obligations, especially when deadlines vary depending on accounting periods and company size. Staying on top of these dates ensures smooth financial management and avoids late payment charges. This post explains key corporation tax deadlines, how to calculate them, and practical tips to help you meet your obligations on time.

Calendar showing marked corporation tax deadlines

Understanding Corporation Tax Deadlines

Corporation tax deadlines depend on your company’s accounting period and when your financial year ends. The main deadlines to remember are:

• Filing your company tax return (CT600)

• Paying your corporation tax bill

  
  

Filing the Company Tax Return

You must file your company tax return within 12 months after the end of your accounting period. For example, if your accounting period ends on 31 March 2023, your tax return deadline is 31 March 2024.

The tax return includes details of your company’s income, expenses, and the tax due. Even if your company made no profit, you still need to file a return.

Paying Corporation Tax

Corporation tax payment deadlines differ based on your company’s taxable profits:

• If your taxable profits are less than £1.5 million, you must pay your corporation tax 9 months and 1 day after the end of your accounting period.

• For companies with profits over £1.5 million, payments are usually made in quarterly installments starting 6 months and 13 days after the start of the accounting period.

  
  

For example, if your accounting period ends on 31 December 2023 and your profits are below £1.5 million, your payment deadline will be 1 October 2024.

How to Calculate Your Deadlines

Calculating deadlines can be confusing, but breaking it down helps:

1. Identify your accounting period end date. This is usually your financial year-end.

2. Add 12 months to find your tax return filing deadline.

3. Add 9 months and 1 day to find your corporation tax payment deadline if profits are under £1.5 million.

4. For larger profits, calculate quarterly payment dates starting 6 months and 13 days after the accounting period begins.

   
   

Example Calculation

Suppose your company’s accounting period runs from 1 January 2023 to 31 December 2023:

• Tax return deadline: 31 December 2024

• Tax payment deadline (profits under £1.5 million): 1 October 2024

• If profits exceed £1.5 million, quarterly payments start on 14 July 2023, then 14 October 2023, 14 January 2024, and 14 April 2024.

  
  

Practical Tips to Avoid Missing Deadlines

Missing deadlines can result in penalties starting from £100 and increasing over time. Here are some tips to stay on track:

• Set reminders early. Use digital calendars or accounting software to alert you weeks before deadlines.

• Keep financial records updated throughout the year. This reduces last-minute stress when preparing returns.

• Work with an accountant or tax advisor. They can help calculate deadlines and prepare your return accurately.

• File online. HMRC’s online system confirms receipt immediately, reducing the risk of lost paperwork.

• Plan for payments. Set aside funds regularly to cover your corporation tax bill.

  
  

Desk with laptop displaying tax software and financial papers

What Happens if You Miss a Deadline

Failing to meet corporation tax deadlines triggers penalties and interest charges:

• Late filing penalty: £100 if up to 3 months late, increasing with time.

• Late payment interest: Charged daily on unpaid tax from the due date.

• Additional penalties: For very late returns or repeated failures.

  
  

HMRC may also investigate if deadlines are repeatedly missed, which can lead to further complications.

Staying Ahead with Corporation Tax Deadlines

Corporation tax deadlines are fixed and non-negotiable. The best way to avoid penalties is to plan ahead and maintain good financial habits. Here are some final recommendations:

• Review your accounting period dates annually.

• Use software tools designed for tax management.

• Communicate with your finance team or accountant regularly.

• Keep a checklist of all tax-related deadlines and tasks.