Cumulative quarterly updates: the part everyone gets wrong
The single most misunderstood thing about MTD is what a quarterly update actually contains. Get this once and it is obvious forever.
Every quarterly update restates your totals from 6 April to the end of that quarter — not just the latest three months. Each update *replaces* the last one with a fuller running total. This is what 'cumulative' (or 'year-to-date') means, and it is by far the most common thing people get wrong: they assume they submit each quarter in isolation.
A full year, worked through
Imagine a sole trader whose actual quarter-by-quarter activity looks like this:
| The quarter's own activity | Income | Expenses |
|---|---|---|
| Q1 (6 Apr – 5 Jul) | £8,000 | £3,000 |
| Q2 (6 Jul – 5 Oct) | £6,000 | £2,000 |
| Q3 (6 Oct – 5 Jan) | £10,000 | £4,000 |
| Q4 (6 Jan – 5 Apr) | £9,000 | £3,500 |
But the figure you actually submit each quarter is the running total since 6 April:
| Update & deadline | Income submitted (cumulative) | Expenses submitted |
|---|---|---|
| Update 1 — 7 Aug 2026 | £8,000 | £3,000 |
| Update 2 — 7 Nov 2026 | £14,000 | £5,000 |
| Update 3 — 7 Feb 2027 | £24,000 | £9,000 |
| Update 4 — 7 May 2027 | £33,000 | £12,500 |
Update 2's £14,000 is Q1's £8,000 plus Q2's £6,000. Update 4's £33,000 is the whole year. Each update simply carries everything so far.
Because every update restates the whole year, fixing a mistake is painless. Say you realise after Update 1 that a £500 sale was missed. You do not resend Update 1 or file an amendment — you just add the £500 to your records, and Update 2's cumulative total automatically includes it (£14,500 instead of £14,000). The correction rides along in the next update. HMRC designed it this way on purpose.
Three things to remember
- A quarterly update never calculates your tax and never asks for a payment. It is an information return only.
- If a quarter is quiet, you still send an update — it just shows the same running total as before. A 'nil' movement is fine.
- The numbers do not need to be perfect yet. Accounting adjustments, allowances and reliefs are all applied later, at the final declaration.
One practical warning: because updates are cumulative, a spreadsheet that only ever shows the current quarter in isolation is not doing the job. A good tracker keeps a live year-to-date figure so that what you copy into your submission is always the correct cumulative total.
Sources: HMRC 'Send quarterly updates' guidance and the Making Tax Digital quarterly-update direction on gov.uk. General information, not tax advice.
General information, not tax or financial advice. Always confirm your own position with HMRC or a qualified adviser. This article was last checked against published gov.uk guidance on 13 July 2026. Rules and figures can change — always confirm your own position with HMRC or a qualified adviser.