A quarterly update is the year so far.

Clients tend to think of a quarterly update as a small return for the last three months. Under Making Tax Digital for Income Tax it is not. HMRC's guidance says each update covers from the start of the tax year to the end of the update period, not just the previous three months.

So the figure a practice signs off each quarter is the year to date. That is worth holding on to, because it decides what you are reviewing, what a new client brings with them, and how a mistake is put right.

What HMRC is sent

An update is a set of totals for each income source: one for each category of income and of expense. HMRC is not sent the invoices and receipts behind them.

Take a sole trader with £12,000 of turnover and £3,000 of expenses by 5 July, and a further £10,000 and £2,500 by 5 October. The first update sends £12,000 and £3,000. The second sends £22,000 and £5,500.

A client who joins you mid-year

This is the part that catches practices out. If a client comes to you in September, the first update you file for them is not for their last three months. It carries every month since 6 April, including the ones you never saw.

Before you file it, ask what is already in their records for the earlier months and whether anything has been sent to HMRC. Your figure replaces whatever HMRC holds, so it has to be the whole year so far.

The four deadlines

• 6 April to 5 July: update due by 7 August
• 6 April to 5 October: due by 7 November
• 6 April to 5 January: due by 7 February
• 6 April to 5 April: due by 7 May

An update can be sent at any time from the end of its period to the deadline. It can also be sent up to 10 days before the period ends, if no further transactions are expected.

Decide calendar periods before the first update

A client whose books run from 1 April to 31 March can use calendar update periods, which end on 30 June, 30 September, 31 December and 31 March. The deadlines stay the same.

The choice is made in software, for each income source, before the first update is sent. Once an update has gone for a tax year, the periods for that year cannot be changed. So it is a question for each client at the start of the year, not one to come back to.

A mistake is put right by the next update

Because each update carries new running totals, a client who finds a missed May expense in September just records it, and the next update includes it. In HMRC's words, you can correct your records without having to resend previous updates.

The end of the year is different. If the records need changing after the fourth update, HMRC says you may need to send that fourth update again, and to do so before making any tax adjustments.

A quiet quarter, and a late one

A client who received no income and incurred no expenses in a period must still send the update. No accounting or tax adjustments are needed before an update is sent; those belong to the year end.

HMRC has said it will not apply penalty points for late quarterly updates during the 2026 to 2027 tax year. Points still apply to a late tax return. After that year a late update earns a point, and four points bring a £200 penalty.

Review the year to date, not the quarter. A figure can look right for three months and still be wrong for the year, and the year is what HMRC holds.

DoneTax+ shows the year-to-date figures HMRC will be sent, category by category, before you file each quarter.

Sources, read on 11 October 2026: Send quarterly updates; Get ready for MTD: an agent toolkit. This is a guide to HMRC’s published guidance, not tax advice.