Corporation Tax Late Filing Penalties Have Doubled: What Bury Companies Need to Check Now

If your company's Corporation Tax return has ever run late, doing so again just got a lot more expensive. From 1 April 2026, HMRC doubled the flat-rate fines for late Company Tax Returns (CT600s) — the first increase to these amounts since they were set in 1998. The change applies by filing deadline rather than accounting period, so even a company with a 2025 year end can be caught if its filing deadline falls on or after 1 April 2026.

What's Actually Changed

The fixed penalties that apply regardless of how much tax is owed have doubled across the board:

• A return up to 3 months late: £100, now £200

• A return more than 3 months late: £200 total, now £400

• Third consecutive late return, up to 3 months late: £500, now £1,000

• Third consecutive late return, more than 3 months late: £1,000, now £2,000

The Tax-Geared Penalties Haven't Moved — But They Still Stack

Separately from the flat fines, HMRC's tax-geared surcharges are unchanged: if Corporation Tax is still unpaid and the return is six months late, HMRC adds a 10% surcharge on the estimated tax due, with a further 10% added at twelve months. Those surcharges sit on top of the new, higher flat-rate fines rather than instead of them, so a seriously late return with unpaid tax attached is now noticeably more expensive than it was a year ago.

Why This Is Worth Checking Now

HMRC paused automatic late-filing penalty notices for several months while it updated its systems, then resumed sending them out in August 2026. Any company that filed late during that pause, and assumed the silence meant the matter had been overlooked, may now be receiving a penalty notice it wasn't expecting, calculated at the new, doubled rate if the filing deadline fell on or after 1 April 2026.

Who's Affected

This applies to any UK limited company required to submit a Company Tax Return, including:

• Owner-managed and family companies

• Contractors trading through a personal service company

• Dormant or non-trading companies, unless HMRC has been formally told the company is dormant

• Companies that have filed late before, since the repeat-offender rates apply after three consecutive late returns

Importantly, the penalty is triggered by late filing alone. A company that made no profit, owes no tax, or has since stopped trading can still be fined if the return itself wasn't submitted on time.

What To Do Now

A few straightforward checks can avoid an unwelcome letter:

• Confirm your actual filing deadline, normally 12 months after the accounting period ends, which is separate from the payment deadline of nine months and a day after period end

• If a company is dormant, make sure HMRC has actually been notified, since dormant status isn't automatic

• If a return is already overdue, get it filed as soon as possible, since the flat penalty increases again at the three-month mark

• If a penalty notice has arrived unexpectedly, check the filing date before assuming it's correct, as appeals are possible in limited circumstances such as a reasonable excuse

Jackson Lee Accountants, based in Bury, helps local companies keep on top of filing deadlines and deal with HMRC correspondence when it does arrive. If you're not sure when your next Company Tax Return is due, or you've received a penalty notice you weren't expecting, get in touch and we'll take a look.