Corporation Tax: pay before the return filing deadline

Two deadlines from one accounting period

The Company Tax Return deadline is generally 12 months after the end of the accounting period. Payment is usually due 9 months and 1 day after it ends. When HMRC has sent a notice to deliver a return, the company must file even if it made a loss or has no tax to pay.

This article assumes a company outside the instalment regime, a normal 12-month accounting period and a notice to deliver received in the ordinary way. Unusual notice timing can affect the filing date, so check the notice itself.

Start from the tax period

A Corporation Tax accounting period is not always the same as the period covered by the company's accounts. A first financial year can contain two tax periods, each with its own payment date and return. Take payment dates from the Corporation Tax periods, not from the accounts cover page.

Companies House filing adds a third deadline. Annual accounts for a private limited company are normally due 9 months after the end of its financial year.

Check the instalment threshold before relying on the ordinary date

HMRC's general payment guide uses profits of £1.5 million to separate ordinary payment from instalments. The Company Taxation Manual at CTM92520 explains that the threshold is reduced for short accounting periods and where a company has associated companies.

Profits below an unadjusted £1.5 million do not by themselves confirm that the 9 months and 1 day date applies. Work out the threshold that fits the company's period length and associated companies before scheduling the payment.

Hypothetical example: a 31 March 2026 year end

In this hypothetical, a private company outside the instalment regime has a Corporation Tax period from 1 April 2025 to 31 March 2026, matching its accounts, and received its notice in the normal way.

The payment falls due almost three months before the return. Preparing the tax computation alongside the accounts gives the company a figure to fund in December, instead of waiting for the March filing to discover it.

The nominal due date is 1 January 2027. If a deadline falls on a weekend or bank holiday, the money must reach HMRC on the working day before it, unless the payment is made by Faster Payments using online or telephone banking. Whichever method is used, allow for its processing time instead of assuming a bank will process a payment on the due date itself.

Use the reference for the period being paid

Each payment needs the 17-character payment reference for the accounting period it covers. The reference changes each period, so a bank payee saved from last year can carry an old reference into this year's payment.

A return acknowledgment shows that the return was submitted. It says nothing about whether the payment arrived or reached the right period, so confirm receipt and allocation separately. A practical record for each period includes the items below.

• The version of the tax computation used to set the payment
• The payment reference, checked against the current period before paying
• The bank payment confirmation and the date it was sent
• HMRC's record showing the payment received and allocated to the period
• The return submission acknowledgment
• The current tax payable reconciliation tying the ledger to the payment