Corporation Tax deadlines: when to pay and file

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Pay first, file later

Corporation Tax has an unusual order. The money is due before the paperwork. For a 31 March year end, your Corporation Tax must be paid by 1 January (9 months and one day later), but the CT600 return isn’t due until 31 March the following year (12 months later). It’s a common trap: directors assume the payment lines up with the filing deadline and end up paying late without realising. We work your figures out well before the payment date so you know exactly what’s due and when.

Deadlines by accounting year end

Your dates depend entirely on when your accounting year ends. Here is how the common year ends fall:

Pay date = 9 months and 1 day after year end; file date = 12 months after year end. The pay date always comes first.

How to pay Corporation Tax

You pay HMRC using your 17-character Corporation Tax payment reference for the specific accounting period. It changes every period, and using the wrong one (last period’s, for example) is a common error that sends the payment to the wrong place. Faster methods, online or telephone banking and CHAPS, clear the same or next working day. Bacs, direct debit (if you have already set one up) and debit card take about three working days, so allow time before the deadline.

Large companies: quarterly instalments

If your profits are over £1.5 million, you don’t get the 9-month-and-a-day rule. Instead you pay Corporation Tax in four quarterly instalments:

• Large companies (profits over £1.5 million): four instalments due in months 7, 10, 13 and 16 from the start of the accounting period, so two fall during the year and two after it.
• Very large companies (profits over £20 million): an earlier schedule, with instalments in months 3, 6, 9 and 12, all within the accounting period.

The £1.5 million and £20 million thresholds are divided between associated companies, so a group reaches them sooner. If you’re approaching this level it changes your cash-flow planning, and we set it up ahead of time.

Long accounting periods

An accounting period longer than 12 months (common in a company’s first year) is split into two for Corporation Tax, usually the first 12 months and then the remainder. Each part has its own return and its own deadlines. We handle the split so nothing is missed.

Penalties and interest

Miss the filing deadline and HMRC charges an automatic £100 penalty, another £100 if you’re three months late, then 10% of the unpaid tax at six months and a further 10% at twelve months. Pay the tax itself late and HMRC charges interest from the due date. None of this is worth risking over a missed diary date, which is why we manage both deadlines for you.

Don’t forget to notify HMRC

A new company must tell HMRC it’s active (usually within three months of starting to trade) so it’s set up for Corporation Tax. Getting registered correctly at the start avoids problems later, and it’s part of what we handle when we take you on.

Want both dates handled for you? See the full Corporation Tax guide, check the Corporation Tax rates and marginal relief, work out your bill with our Corporation Tax calculator, or take our 2-minute quiz.