For the first time since the regime was introduced in the late 1990s, HMRC has doubled the fixed penalties for filing a Company Tax Return late. From 1 April 2026 a return that is one day late costs 200 pounds rather than 100. Three months late costs 400 rather than 200. Where a company has now filed late three times running, the figures move from 500 and 1,000 pounds to 1,000 and 2,000. HMRC expects the change to raise an extra 45 million pounds in 2026/27, rising to around 70 million a year by 2030/31.
The measure was confirmed at Autumn Budget 2025 and applies to any Company Tax Return with a filing date on or after 1 April 2026. That last detail is the one most business owners will miss. It catches returns for accounting periods that ended well before April, so a company that has been quietly drifting for a year is already exposed at the new rate rather than the old one.
What exactly changed on 1 April 2026?
The fixed late filing penalties doubled across the board. One day late is now 200 pounds instead of 100, and three months late is 400 instead of 200. Where a company files late for a third consecutive period, the penalties rise to 1,000 and 2,000 pounds respectively, up from 500 and 1,000. The tax-geared surcharges that bite at six and twelve months are unchanged.
The stated reasoning is straightforward. A 100 pound penalty set in the late 1990s has been eroded by nearly three decades of inflation to the point where it stopped deterring anybody. Doubling it restores roughly the sting the original figure had. Whether that works as deterrence is a question for HMRC. What matters commercially is that a number which was small enough to ignore has become a number clients ask about.
Does it apply to companies that owe no tax?
Yes. The fixed penalties are triggered by the return being late, not by there being tax to pay. A company with no corporation tax liability, or one that has traded at a loss, still gets the full 200 pounds at one day late. Dormant companies that have never told HMRC they are dormant are in scope too, because HMRC is still expecting a return.
This is the part that generates the most client confusion, and it is worth saying plainly in any communication a practice sends out. Business owners reason from the tax bill. If they owe nothing, they assume the filing is a formality. The penalty regime does not work that way, and the first time somebody learns that is usually when the letter arrives.
Which clients are actually at risk?
Not the ones a practice worries about. The organised clients file on time because their accountant chases them. The exposure sits in the corners of a client list: the dormant holding company nobody thinks about, the second trading entity a client set up and half forgot, the newly incorporated business that has not yet understood that Companies House and HMRC want different things on different dates.
Those are also the entities where a firm has the least visibility, because they generate the least fee income and therefore the least attention. A practice that runs a deliberate sweep of every entity it is named on, rather than every client it actively bills, will usually find two or three that are drifting. Finding them in July is a service. Finding them in the penalty letter is a complaint.
Why is a penalty increase a marketing moment?
Because it converts a dull administrative fact into a question business owners will type into Google. When a cost doubles, people search. Phrases like what happens if my company tax return is late, or how much is the corporation tax penalty now, become live queries with genuine volume and almost no competent content behind them.
That is the opening. A national term such as accountants near me is a multi-year fight against firms with far more authority. A specific, timely question that a few hundred UK business owners will type this quarter is a single page and a week of work. The wider version of this argument, and the framework behind it, sits in our complete guide to digital marketing for accounting firms.
What does a firm publish about this?
One page, in plain English, that states the old figures and the new ones side by side, confirms that the penalties apply even where no tax is due, and explains the filing date rule that catches earlier accounting periods. No PDF. No newsletter attachment. A findable page on the practice website, because the point is to be there when somebody searches rather than to be read by the clients who already open your emails.
Then make the page do its job. It has to rank for the questions being asked, which is the work of search engine optimisation. It has to let a worried director act immediately instead of bouncing, which is the work of website design and development. And the same message needs to reach every existing client before HMRC's own correspondence does, which is the work of email and lifecycle marketing. The full picture for practices in this market sits on our page for digital marketing for UK accounting firms.
A worked example
Two practices in the same city both spot the change in April. The first updates its internal filing calendar and moves on, which is correct and invisible. The second does the same thing, then spends an afternoon writing a 700-word explainer, publishes it, and emails every client a three-line summary with a link.
In September a local director gets a penalty notice for a dormant company he forgot he owned. He searches for whether the penalty applies when no tax is due. He lands on the second practice's page, which answers the question in the first paragraph and does not try to sell him anything for four hundred words. There is a way to book a call at the bottom. Both firms were equally competent. Only one of them was present at the moment the client went looking.
How does this fit the rest of the 2026 compliance calendar?
It is one of several changes that quietly reprice being disorganised. Companies House identity verification changed who is allowed to file, and the accounts reforms landing in 2028 will change what small companies must publish. We covered both in our analysis of Companies House identity verification for accountants and our piece on the 2028 Companies House accounts reforms.
The pattern across all of them is the same. Each is administrative on its face and commercial underneath, because each gives a client a fresh reason to work out whether their adviser is ahead of things or behind them. Firms that treat each change as a filing task get through it. Firms that treat each as a reason to be publicly useful pick up the clients of the firms that said nothing, which is the growth pattern documented in our guide to digital marketing for UK accounting firms in 2026.
How should the client message actually read?
Short, specific and free of tax vocabulary. The old figure, the new figure, the date it changed, one line confirming that it applies with no tax due, and one line telling the client what you have already done about it on their behalf. That last element is the one most firms leave out, and it is the only part that makes the message feel like service rather than a warning.
The temptation is to write something comprehensive. Resist it. A director skims for two things: does this cost me money, and do I need to do anything. A message that answers both in the first four lines gets read. A message that opens with a paragraph about Finance Act provisions gets archived, and the client learns nothing except that their accountant sends long emails.
There is a sequencing point too. Send it before the quarter's filing reminders rather than bundled with them, because a message that arrives attached to a request for records reads as chasing. A standalone note that asks for nothing reads as looking after somebody, and it is the same information either way.
Is there an argument for saying nothing?
There is an argument that publicising penalties makes clients anxious, and that a practice which never raises the subject appears calm. It does not survive contact with how people actually behave. Clients find out either way, because HMRC writes to them and the trade press covers it. The only variable a firm controls is whether the first explanation they read came from their own adviser or from a stranger.
There is also a quieter risk in silence. A director who receives a doubled penalty and realises their accountant never mentioned the change does not conclude that the accountant was being calm. They conclude that the accountant was not paying attention, and that is a difficult impression to reverse.
What to do in the next four weeks
Run the entity sweep first, including dormant and non-billing companies, because a client who never gets a penalty never needs the explainer. Then write the client-facing page and publish it as a page rather than an attachment. Send it to the full list with one sentence confirming that you have already checked their filings. Keep the language non-technical, because the people who most need this are the ones who do not read tax notes.
Triomatic Marketing builds the visibility side of this for accounting firms across the UK and USA. We are AI-powered and founder-led, and we treat a compliance change as what it actually is for a practice, which is a scheduled moment when clients decide whether their adviser is ahead or behind. To talk it through, message Aria on WhatsApp via triomaticmarketing.com, or book a free 15-minute discovery call at https://calendly.com/hello-triomaticmarketing/15min.
Frequently asked questions
FAQs
How much is the corporation tax late filing penalty in 2026?
From 1 April 2026 a Company Tax Return filed one day late attracts a 200 pound penalty, up from 100. At three months late it is 400 pounds, up from 200. A third consecutive late filing raises those to 1,000 and 2,000 pounds respectively.
Do the penalties apply if the company owes no corporation tax?
Yes. The fixed penalties are triggered by the return being late rather than by there being tax to pay. A loss-making company, or one with no liability, still faces the full amount, and companies that have not told HMRC they are dormant remain in scope.
Does the increase affect accounting periods that ended before April 2026?
It can. The new rates apply to any Company Tax Return with a filing date on or after 1 April 2026, which includes returns for accounting periods that ended earlier. A return that is already overdue is therefore exposed at the higher rate.
Why did HMRC increase the penalties now?
The fixed amounts had not risen since the regime was introduced in the late 1990s, and inflation had eroded their deterrent effect. The change was confirmed at Autumn Budget 2025, and HMRC expects it to raise around 45 million pounds in 2026/27 rising to about 70 million a year by 2030/31.
Why should an accounting firm publish anything about this?
Because a cost that doubles creates searches. Business owners look up what the penalty is now and whether it applies with no tax due. Those are low-competition, high-intent queries that a small practice can rank for quickly, and almost nobody in the profession is writing for them.
How does Triomatic Marketing help with this?
We build the page that ranks for the questions worried directors are typing, the conversion path that turns a reader into a booked call, and the email that reaches every existing client first. Book a free 15-minute call at https://calendly.com/hello-triomaticmarketing/15min to scope it.