Corporation Tax Deadlines: What Happens If You File or Pay Late?

Keeping up with Corporation Tax deadlines is an important part of running a limited company. Missing a deadline can lead to penalties, additional costs and unnecessary complications with HMRC.

The good news is that the deadlines are straightforward once you understand the difference between filing your Company Tax Return and paying your Corporation Tax.

When Is Corporation Tax Due?

A company normally has 12 months from the end of its accounting period to file its Company Tax Return.

However, Corporation Tax itself is due earlier. It must usually be paid nine months and one day after the end of the accounting period.

For example, if your company’s accounting period ends on 31 March 2026:

• Corporation Tax payment deadline: 1 January 2027
• Company Tax Return filing deadline: 31 March 2027

Although the tax payment deadline comes before the tax return filing deadline, many companies choose to prepare and submit their return before paying the tax. This allows them to know exactly how much Corporation Tax they need to pay.

But what happens if the return or payment is late?

Penalties for Filing Your Company Tax Return Late

HMRC can charge a penalty even if your Company Tax Return is only one day late.

If the return remains outstanding, further penalties can apply at three, six and 12 months after the deadline.

This means that delaying your Company Tax Return can become increasingly expensive, particularly where a significant amount of Corporation Tax is due.

Higher Penalties for Repeated Late Filing

Companies that repeatedly file their tax returns late can face higher penalties.

If a Company Tax Return is filed late three times in a row, the standard £200 penalties are increased to £1,000 each.

This makes it particularly important for businesses to keep track of their Corporation Tax deadlines and avoid repeated delays.

Can You Appeal a Late Filing Penalty?

If you have a reasonable excuse for filing your Company Tax Return late, you may be able to appeal the penalty.

However, the company must first submit the outstanding tax return before making the appeal.

Whether an excuse is accepted will depend on the circumstances and HMRC’s assessment of the situation.

What Happens If You Do Not File Your Return?

If your Company Tax Return has still not been filed six months after the deadline, HMRC can estimate how much Corporation Tax it believes the company owes.

This is known as a tax determination.

A company cannot appeal against a tax determination itself. However, once the company files its actual Company Tax Return and pays the Corporation Tax due, HMRC can recalculate the penalties and interest based on the company’s actual tax liability.

What If Corporation Tax Is Paid Late?

Late payment of Corporation Tax is treated differently from late filing.

There is no separate late-payment penalty, but HMRC will charge interest on the unpaid tax.

Interest is charged at a rate of 4% above the Bank of England base rate, running from the Corporation Tax payment deadline until the tax is paid.

This means that even where a late payment does not result in a penalty, it can still increase the overall cost to the company.

Avoid Unnecessary Costs

Corporation Tax deadlines are easy to overlook, particularly when a business is busy with its day-to-day operations. Filing the Company Tax Return on time and paying the Corporation Tax by the correct date can help your company avoid unnecessary penalties and interest.

If you are unsure about your Corporation Tax deadline or how much tax your company needs to pay, it is worth getting professional advice before the deadline rather than dealing with the consequences afterwards.

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