Missing a Company Tax Return deadline can now result in significantly higher penalties than under the previous Corporation Tax filing regime.
For Company Tax Returns with a filing date on or after 1 April 2026, the standard late-filing penalty starts at £200. If the return remains outstanding for more than three months, the flat-rate penalties can total £400.
Higher penalties apply where a company repeatedly files late, while returns that remain outstanding for six or twelve months can also trigger tax-related penalties based on unpaid Corporation Tax.
This guide explains the current CT600 late-filing penalties, what changed from April 2026, how repeated late filing is treated, the difference between filing penalties and late-payment interest, and when a penalty may be appealed.
Need help with an overdue Company Tax Return?
What Changed to Corporation Tax Late Filing Penalties From April 2026?
HMRC increased the fixed late-filing penalties for Company Tax Returns whose filing date falls on or after 1 April 2026.
The change doubled the previous flat-rate penalties.
| Filing position | Before 1 April 2026 | Filing date on/after 1 April 2026 |
|---|---|---|
| Return filed within 3 months after deadline | £100 | £200 |
| Return more than 3 months late | £200 | £400 |
| Third and successive consecutive late returns, within 3 months | £500 | £1,000 |
| Third and successive consecutive late returns, more than 3 months late | £1,000 | £2,000 |
These are filing penalties. They can apply even where the company has no Corporation Tax to pay, provided HMRC required the company to submit a Company Tax Return.
What Happens If the Company Tax Return Is 6 or 12 Months Late?
The penalties become more serious when a Company Tax Return remains outstanding for a long period.
6 months late: HMRC can issue a tax determination estimating the company’s Corporation Tax liability and add a penalty equal to 10% of the unpaid Corporation Tax.
12 months late: a further penalty of 10% of the unpaid Corporation Tax can apply.
These tax-related penalties are in addition to the flat-rate late-filing penalties.
If HMRC makes a tax determination, the company should file the outstanding Company Tax Return so HMRC can replace the estimate with the actual tax position.
Late Filing Penalties and Late Payment Interest Are Different
A late-filing penalty relates to submitting the Company Tax Return after its filing deadline.
Late-payment interest is different. It can arise where Corporation Tax itself is paid after the payment deadline.
HMRC’s published Corporation Tax late-payment interest rate is currently 7.75% from 9 January 2026. HMRC interest rates are linked to the Bank of England base rate, so this figure can change.
Because the rate can change, companies should check HMRC’s current interest-rate guidance rather than assuming 7.75% will apply indefinitely.
Company Tax Return and Corporation Tax Payment Deadlines
The filing deadline and payment deadline are separate.
For most companies:
Corporation Tax payment: normally due 9 months and 1 day after the end of the accounting period.
Company Tax Return: normally due 12 months after the end of the Corporation Tax accounting period.
Companies that fall within the quarterly instalment payment regime have different Corporation Tax payment rules.
Read: How to file a Company Tax Return
Corporation Tax rates: How much Corporation Tax a limited company pays
Corporation Tax Late Filing Penalty Timeline
- 1 day late: £200
- More than 3 months late: flat-rate penalties total £400
- 6 months late: HMRC can estimate the Corporation Tax liability and add 10% of unpaid tax
- 12 months late: a further 10% of unpaid tax can apply
Different flat-rate amounts apply where the company has repeatedly filed late for consecutive accounting periods.
What Happens If a Company Files Late Repeatedly?
Higher flat-rate penalties apply where a company repeatedly fails to submit Company Tax Returns on time.
Where returns for three or more consecutive accounting periods are filed late, the penalty for the third and subsequent consecutive failures can rise to:
- £1,000 where the return is delivered within three months after the filing deadline
- £2,000 where it is delivered more than three months late
The increased rates continue for successive accounting periods until the company files a return on time. Once an accounting period is filed on time, a later failure starts again at the normal penalty rates.
Can You Appeal a Corporation Tax Late Filing Penalty?
Yes. A company may be able to appeal a Corporation Tax late-filing penalty where it has a reasonable excuse or believes the penalty is incorrect.
HMRC states that the outstanding Company Tax Return must be filed before appealing a late-filing penalty.
A reasonable excuse depends on the facts and circumstances. Simply being busy, having no Corporation Tax to pay, or relying on an agent who was slow to act will not normally be enough on its own.
If a penalty notice has been received, deal with both the outstanding return and the penalty promptly rather than allowing additional penalties to build up.
How to Avoid Corporation Tax Late Filing Penalties
Here’s what we recommend clients implement immediately:
File before the Company Tax Return deadline
Aim to finalise the accounts and Corporation Tax computation well before the statutory filing deadline.
Keep the filing and payment deadlines separate
Corporation Tax is normally payable before the Company Tax Return itself is due, so both dates should be monitored independently.
Keep accounting records up to date
Waiting until close to the deadline to resolve bookkeeping or accounting problems increases the risk of late filing.
Act quickly if a deadline has already been missed
Filing as soon as possible can prevent the delay moving into the next penalty band.
Get Help With an Overdue Company Tax Return
If your Company Tax Return is approaching its deadline or is already overdue, dealing with it quickly can reduce the risk of further penalties.
Accounting People can help prepare the company’s accounts, Corporation Tax computation and CT600, confirm the relevant deadlines and submit the Company Tax Return to HMRC.
If you have already received a Corporation Tax penalty, we can also help you understand the filing position and the steps needed to bring the company’s affairs up to date.
Speak to our Corporation Tax accountants
Read: How to file a Company Tax Return
Frequently Asked Questions About Corporation Tax Late Filing Penalties
What is the penalty for filing a Company Tax Return late?
For Company Tax Returns with a filing date on or after 1 April 2026, the standard late-filing penalty is £200. If the return remains outstanding for more than 3 months, a further £200 applies, taking the flat-rate penalties to £400.
What happens if a CT600 is more than 6 months late?
If a Company Tax Return is 6 months late, HMRC can estimate the Corporation Tax liability through a tax determination and add a penalty equal to 10% of the unpaid Corporation Tax. The company should still file the outstanding return so HMRC can recalculate the actual tax, interest and penalties due.
What happens if the Company Tax Return is 12 months late?
If the return remains outstanding for 12 months, a further penalty of 10% of any unpaid Corporation Tax can apply. This is in addition to the earlier late-filing penalties.
Is there a penalty if no Corporation Tax is due?
Yes. Fixed late-filing penalties can still apply where HMRC has required the company to submit a Company Tax Return, even if the company ultimately has no Corporation Tax to pay. The flat-rate penalty is triggered by failing to file the required return by the deadline.
What happens if a company repeatedly files its Company Tax Returns late?
Higher penalties apply where a company repeatedly files late. For the third and subsequent consecutive late returns, the flat-rate penalty can increase to £1,000 where the return is filed within 3 months after the deadline, and £2,000 where it is more than 3 months late.
Can you appeal a Corporation Tax late filing penalty?
Yes. A company can appeal where it has a reasonable excuse or believes the penalty is incorrect. HMRC requires the outstanding Company Tax Return to be filed before an appeal against the late-filing penalty is made. Whether an excuse is reasonable depends on the circumstances of the case.
