Corporation Tax Quarterly Instalment Payments 2026/27

Two payment regimes

Most small companies pay corporation tax in one go, nine months and one day after the end of their accounting period. Large companies do not get that luxury. They must estimate their liability up front and pay it in quarterly instalments, partly during the accounting period itself.

For 2026/27 the corporation tax rates remain 19% up to GBP 50,000, 25% from GBP 250,000 and marginal relief in between. The instalment rules sit on top of that and only change when you pay, not how much.

When you become large

A company is large for instalment purposes when its taxable profits exceed GBP 1.5 million. As with the rate thresholds, this limit is divided by the number of associated companies plus one. A group of three associated companies would each become large at GBP 500,000 of profit rather than GBP 1.5 million.

There is also a very large tier at GBP 20 million, again shared across associates, which brings the instalment dates forward further.

When instalments fall due

For a standard 12-month accounting period, a large company pays in four instalments due in:

• Month 7 from the start of the period.
• Month 10.
• Month 13 (one month after the period ends).
• Month 16.

Each instalment is broadly one quarter of the estimated total liability, which means you are paying tax before you even know your final profit.

A worked example

Your company has a year ending 31 March 2027 and expects GBP 2 million of taxable profit, with no associated companies, so it is large but not very large.

• Estimated corporation tax at the 25% main rate is GBP 500,000.
• Four instalments of GBP 125,000 each.
• Due dates: 14 October 2026, 14 January 2027, 14 April 2027 and 14 July 2027.

You must forecast profit during the year to get the early instalments right. Underpaying risks interest charges, while overpaying ties up cash you could use elsewhere.

Practical points

• Profits include chargeable gains, not just trading profit.
• Estimates should be revised at each instalment as your forecast firms up.
• HMRC charges interest on underpaid instalments and pays interest on overpayments.
• The GBP 1.5m and GBP 20m limits are pro-rated for short accounting periods.
• A company that was not large in the prior year and has profits up to GBP 10 million can be exempt from instalments for that year.

The bottom line

For 2026/27, companies with profits above GBP 1.5 million, shared across associated companies, must pay corporation tax in quarterly instalments rather than in a single later payment. A GBP 2 million profit company faces four GBP 125,000 instalments starting in month seven of the year.

Forecast your liability with the calchub.uk corporation tax calculator, and confirm the instalment thresholds, dates and interest rules on gov.uk well before your first payment date.