# Corporation Tax Late Filing Penalties Doubled in 2026

> Here's how VAT repayments from HMRC actually work in 2026, how long they take, and how to avoid the bank details fraud that increasingly targets them.

Last updated: 2026-09-17

*Blog | by Josh Clarke | September 2026*

# Corporation Tax Late Filing Penalties Have Doubled: What Missing Your CT600 Deadline Now Costs

### Josh Clarke

A director we spoke to recently assumed a late company tax return was a minor administrative slap on the wrist, the sort of thing you sort out and move on from. That assumption has become considerably more expensive to hold. From 1 April 2026, HMRC doubled its fixed penalties for late filing of a Corporation Tax return (the CT600), and it has since resumed sending out penalty notices after a pause to its systems earlier in the year. If your company's accounting period has a filing deadline that falls on or after that date, which by now is every live filing, the numbers below are the ones that actually apply to you.

## What actually changed on 1 April 2026?

HMRC's fixed late filing penalties for Corporation Tax returns doubled for any return with a filing deadline falling on or after 1 April 2026. The rate itself, the flat fees charged simply for filing late regardless of whether any tax is actually owed, is what moved. The tax-geared surcharges that kick in for returns that are six and twelve months overdue are unaffected by this specific change, and still work the way they always have.

The practical effect is that a filing pattern which used to cost a company a few hundred pounds in flat penalties over a bad year now costs considerably more, and a business that's been late more than once in a row is exposed to a genuinely uncomfortable bill rather than a token one. HMRC had paused issuing some penalty notices earlier this year while it updated its systems for the change, and recent guidance confirms notices are now going out again, which is why this is worth checking now rather than waiting to see if one arrives.

## How much does a late CT600 actually cost now?

The flat penalty for filing one day late has doubled from £100 to £200. If the return is still not filed three months after that, a further £200 is added on top, bringing the total flat penalty to £400 for a return that's three months late, before any tax-geared surcharge is even considered. Those figures apply regardless of the amount of Corporation Tax actually due.The additional rate threshold has fared even worse. It stood at £150,000 from its introduction in 2010/11 right through to April 2023, when the Autumn Statement 2022 cut it, rather than simply freezing it, to £125,140. That single change dragged a much wider band of higher earners into the 45% additional rate, and the reduced threshold has itself been frozen since.

Beyond three months, the flat penalties stop increasing but a separate, tax-geared surcharge takes over: if the return is still outstanding six months after the deadline, HMRC estimates the tax owed and adds a 10% surcharge on top of that estimate, and if it remains outstanding at twelve months, a further 10% surcharge is applied. That estimate is not something you can simply ignore either, since HMRC's determination stands until a proper return is filed, and it's rarely lower than reality.

What happens if my company is late three years running?

This is where the doubling genuinely bites. If a company files late for a third consecutive accounting period, the flat £200 penalties for that return are increased to £1,000 each, meaning a return that's both a day late and a third consecutive late filing can attract £1,000 immediately, rising to £2,000 in total if it's also more than three months late. A pattern of lateness is treated as a compliance signal in its own right, not just three unrelated slip-ups, and HMRC's penalty structure reflects that directly in the numbers.

It's worth being honest with yourself here about whether "late again" is actually a one-off or a pattern. A single late return caused by a genuinely unusual event, a bereavement, an IT failure, a key person leaving unexpectedly, is a different conversation with HMRC than a third consecutive year of the same excuse, and the penalty regime is deliberately built to make that distinction cost real money rather than just reputation.

Does it matter if my company made no profit, or isn't trading?

No, and this catches out more companies than you'd expect. A Corporation Tax return obligation is based on whether HMRC has issued a notice requiring a return (or the company is otherwise required to notify chargeability), not on whether the company actually made a profit, owes any tax, or is even still trading. A dormant company that HMRC still expects a return from, or a company that made a loss, faces exactly the same flat penalties as a highly profitable one if the return is late.

This is a particularly common trap for a company in its final year, one that's stopped trading, or one that's been quietly dormant while a director focuses elsewhere. If you're not sure whether your company still has an active filing obligation, that's worth confirming directly with HMRC or your accountant rather than assuming inactivity removes the requirement, because the penalty notice arrives regardless of the assumption.

What should I actually do if I think I'm going to miss the deadline?

File an estimate rather than nothing at all if you're genuinely not going to have final figures ready in time, and be upfront with HMRC about why, since a reasonable excuse can sometimes support a successful appeal even where a penalty has already been charged. What HMRC generally won't accept as reasonable is simply being busy, disorganised, or relying on a third party without following up, so the earlier you flag a genuine problem, the more options you tend to have.

The more useful habit, though, is building in enough lead time that the deadline is never a surprise in the first place. At LYA, every client on a fixed monthly fee has their filing deadlines tracked as part of the normal service, not chased up in month eleven, precisely because a deadline that's been on the radar for months rarely turns into an emergency. If your current arrangement means nobody is actively watching your filing dates for you, that's worth changing before the next one, not after.

| Timing | Old flat penalty | New flat penalty (from 1 April 2026) |
| --- | --- | --- |
| 1 day late | £100 | £200 |
| 3 months late (additional, on top of the above) | Additional £100 | Additional £200 |
| 6 months late | 10% of HMRC's estimated tax, on top of flat penalties | Unchanged |
| 12 months late | A further 10% of estimated tax | Unchanged |
| 3rd consecutive late filing (each flat penalty) | £500 | £1000 |

If you're a director juggling more than one compliance deadline this year, our guide to the Companies House identity verification requirement covers the other date currently closing in on every director and PSC. [https://loveyouraccountants.com/knowledge/companies-house-identity-verification-directors-psc](https://loveyouraccountants.com/knowledge/companies-house-identity-verification-directors-psc)

## Frequently asked questions

Is the Corporation Tax filing deadline the same as the payment deadline?

No, and mixing the two up is one of the most common causes of an unexpected penalty. Corporation Tax payment is normally due nine months and one day after the end of your accounting period, while the CT600 return itself isn't due until twelve months after the end of that same period. It's entirely possible to pay on time and still file late, or to assume you have longer than you actually do because the payment deadline has already passed without incident.

Do these doubled penalties apply to every company, or only larger ones?

They apply to every company required to file a CT600, regardless of size, turnover, or whether it's dormant. The doubling applies based on the filing deadline of the return, not the size or trading status of the company, so a small or dormant company is exposed to exactly the same flat penalties as a larger one.

Can a Corporation Tax late filing penalty be appealed?

Yes, HMRC will consider an appeal if you have a reasonable excuse for filing late, such as a genuinely unexpected event outside your control, and act on it without unreasonable delay once it's resolved. Simply being busy, or relying on someone else without following up, generally doesn't meet that bar, so it's worth getting advice on your specific circumstances before assuming an appeal will succeed.

Need help?

If you'd like a second opinion on your company's filing position, want your deadlines actively tracked instead of self-managed, or think a penalty you've already received might be worth appealing, the LYA team is happy to help. Email support.london@loveyouraccountants.com or call 01372 374143, or book a free consultation to get started.

Book a free consultation: [https://loveyouraccountants.com/contact](https://loveyouraccountants.com/contact).

Sources

[Company Tax Returns: Penalties for late filing - GOV.UK](https://www.gov.uk/company-tax-returns/penalties-for-late-filing)

[CT600 penalties are increasing: what limited companies need to know from April 2026 - PayStream](https://www.paystream.co.uk/blog/industry-news/ct600-penalties-are-increasing-what-limited-companies-need-to-know-from-april-2026/)

[Corporation Tax Late Filing Penalties Are Doubling in 2026 - Wright Vigar](https://www.wrightvigar.co.uk/news/corporation-tax-late-filing-penalties-2026)

[SME Tax Update, 3 September 2026 - rossmartin.co.uk](https://rossmartin.co.uk/sme-tax-news/9100-sme-tax-update-3-september-2026)

Tags: compliance, corporation tax, directors, HMRC, limited companies

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**Author**

###### **Josh Clarke**

Josh is our Chief Operating Officer, overseeing operations to ensure a smooth, responsive and high-quality service. With a practical, clear approach...
[Read more](https://loveyouraccountants.com/author-josh-clarke)

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