Understanding Corporate Tax Return Deadlines and Penalties in the UK
TAXNEWS
When you’re running a company in the UK, staying on top of your corporate tax responsibilities isn’t just good practice—it’s a legal requirement. Every limited company must file a corporate tax return, and missing the deadline can lead to penalties, interest, and unnecessary stress. In this blog, we’ll break down the deadline for corporate tax returns, what tax returns your business is required to submit, the penalties for non-compliance, and why professional support can save you time and trouble.
What Tax Returns Do UK Companies Need to File?
Before diving into deadlines, let’s clarify what tax returns a UK company must typically submit:
1. Corporation Tax Return (CT600)
This is the main corporate tax filing. It includes details of your company’s income, expenses, and profit calculations. HMRC uses this return to determine how much Corporation Tax your business owes.
2. Annual Accounts to Companies House
Although not a tax return, your statutory accounts must be filed annually and often align with tax filing requirements. These include:
Profit and loss statement
Balance sheet
Notes to the accounts
Director’s report (depending on company size)
3. Company Tax Computations
These accompany the CT600 and show HMRC how your taxable profit was calculated.
4. VAT Returns (if registered)
If your company is VAT-registered, quarterly VAT returns must also be submitted.
Understanding which returns apply to your business helps ensure you remain fully compliant and avoid penalties.
When Is the Deadline for Corporate Tax Returns?
The deadline for corporate tax returns depends on your company’s accounting period:
Filing the CT600 Return
You must file your corporation tax return within 12 months of the end of your company’s accounting period.
Example:
Accounting period ends: 31 March 2025
CT600 filing deadline: 31 March 2026
Paying Your Corporation Tax
This is a separate deadline. Payment must usually be made 9 months and 1 day after the end of the accounting period.
Example:
Accounting period ends: 31 March 2025
Corporation tax payment deadline: 1 January 2026
Companies House Accounts Deadlines
Private limited companies must submit their annual accounts 9 months after the year-end.
With multiple deadlines to track, it’s easy to miss one if your books aren’t organised well in advance.
Penalties for Missing Corporate Tax Return Deadlines
HMRC enforces strict penalties to encourage timely compliance. Here’s what happens if you miss the CT600 filing deadline:
Late Filing Penalties
1 day late: £100 penalty
3 months late: Additional £100 penalty
6 months late: HMRC issues a tax bill based on its own estimate (“tax determination”)
12 months late: Additional penalty of 10% of unpaid tax
For repeated late filing within three years, the initial penalties double.
Late Payment Penalties
HMRC charges interest on late payments from the day after the due date until the tax is paid. This can add up quickly, especially for companies with large liabilities.
Late Filing of Accounts (Companies House)
1 day to 1 month late: £150
1–3 months late: £375
3–6 months late: £750
More than 6 months late: £1,500
These penalties can escalate if your company repeatedly misses deadlines.
Common Reasons Companies Miss Their Deadlines
Even well-run businesses can slip up. Some typical causes include:
Poor bookkeeping or incomplete records
Confusion about accounting period dates
Staff turnover or internal miscommunication
Lack of tax knowledge or experience
Ignoring HMRC reminders
Fortunately, these issues are preventable with proper systems and professional support.
Get Professional Help for Your Corporate Tax Return
Navigating corporate tax responsibilities doesn’t need to be stressful. At Boobooks, we help UK companies stay compliant, file accurately, and avoid penalties—so you can focus on growing your business.
If you want expert support with your corporate tax return, from preparation to submission, we’re here to help.
Get professional help for your corporate tax return today.