MTD Quarterly Updates: How to Correct a Mistake

If you spot a mistake in a Making Tax Digital quarterly update, you fix the digital record in your software and the corrected figures go to HMRC with your next update. You do not file a separate amendment form, because quarterly updates are running summaries for the tax year, not tax returns. What matters is that every correction is in place before you finalise the year. This guide explains how corrections work, when to resubmit, and what changes once your tax return has gone in.

Key takeaways

• Correct the digital record, not the submitted total.
• Updates are cumulative for the tax year, so the next one picks up your correction automatically.
• You can resubmit sooner if you want an accurate tax estimate now.
• All corrections must be in before the year end submission, due 31 January after the tax year.
• After the tax return is submitted, a mistake is fixed by amending the return.

What is a quarterly update?

Under Making Tax Digital for Income Tax (MTD), sole traders and landlords above the income threshold keep digital records and send HMRC a summary every three months. That summary is the quarterly update. It contains totals of income and expenses by category, taken straight from your digital records. HMRC does not receive the individual invoices or receipts.

Two features make corrections simple. First, a quarterly update is a summary and not a final tax return, and no accounting or tax adjustments are needed in it. Second, each update is cumulative: it covers from the start of the tax year to the end of the latest update period, not just the last three months. HMRC explains this in its guide to using Making Tax Digital for Income Tax.

MTD applies from 6 April 2026 if your qualifying income was over £50,000 in 2024/25, from 6 April 2027 if it was over £30,000 in 2025/26, and from 6 April 2028 if it was over £20,000 in 2026/27. The update deadlines are 7 August, 7 November, 7 February and 7 May. See our guide to MTD quarterly update deadlines for the periods each one covers.

Why errors happen

Most mistakes in quarterly updates are ordinary bookkeeping slips:

• a sale or expense entered twice, often from a bank feed and a manual entry;
• income missed because it was paid in cash or to a different account;
• a transaction put in the wrong category;
• a personal cost recorded as a business expense;
• a typing error in an amount or a date in the wrong tax year;
• a receipt that turned up after the update was sent.

None of these is unusual, and the system is designed to cope with them. The important thing is to correct them when you find them, not to leave them for the year end.

How a correction works

You never edit the figures HMRC already holds. You go back to the digital record that was wrong, such as the duplicated expense or the missing sale, and correct it in your software or spreadsheet. Your software then recalculates the totals for the tax year to date.

From there you have two choices:

• Wait for the next update. Because the next update covers the whole tax year so far, it includes the corrected totals. HMRC's guidance on sending quarterly updates confirms you can correct your records without having to resend previous updates.
• Resubmit now. Most software lets you send an update again. This is worth doing if the error is large and you rely on the in-year tax estimate to set money aside.

If the error comes to light after your fourth update, correct the record and resend the fourth update before you make any year end adjustments.

Before or after the year end submission?

The dividing line is the year end submission, sometimes called the final declaration, which is your tax return for the year. It is due by 31 January after the tax year ends, and it is where accounting adjustments are made. Our article on the MTD final declaration covers that stage.

The rules for amending a return are on GOV.UK under if you need to change your return. Penalties for inaccurate returns depend on the circumstances, so read HMRC's current penalty guidance on GOV.UK. We do not quote the percentages here because they vary case by case. Our guide to MTD penalty points explains the separate system for late submissions.

Step by step: correcting a quarterly update error

1. Identify the exact record that is wrong, with its date, amount and category.
2. Find the evidence: the invoice, receipt or bank statement line that shows the right figure.
3. Correct the digital record in your software. Edit or delete the wrong entry, or add the missing one. Do not post a balancing figure with no explanation.
4. Re-run your checks. Reconcile the bank account for the period so you know nothing else is out.
5. Decide whether to resubmit or let the next update carry the correction.
6. Review the updated tax estimate and adjust what you are setting aside.
7. Before the year end submission, review the whole year once more, resend the fourth update if anything changed, then make your accounting adjustments.

Worked example (illustrative)

"Dalia", an illustrative example, is a self-employed electrician whose qualifying income was over £50,000 in 2024/25, so she joined MTD from 6 April 2026. She sent her first quarterly update, covering 6 April to 5 July 2026, before the 7 August deadline. It showed income of £16,200 and expenses of £5,900.

In October, while reconciling her bank account, she finds two errors in that first quarter. A £1,200 supplier invoice was entered twice, once from the bank feed and once by hand. And an £850 payment from a customer, received into her personal account, was never recorded.

She deletes the duplicate expense and adds the missing sale, attaching the invoice to each record with a note. Her corrected first quarter is income of £17,050 and expenses of £4,700. She does not need to resend the first update. Her second update, due by 7 November 2026, covers 6 April to 5 October 2026 and so includes the corrected figures. Her estimated profit for the year to date is £2,050 higher than it would have been, and she increases the amount she sets aside for tax.

Dalia and her figures are invented for illustration and are not a real client.

Common mistakes

• Leaving corrections until January. Small errors are easy to trace in the month they happen and hard to trace nine months later.
• Posting a lump-sum adjustment. Correct the actual record so there is a trail back to the evidence.
• Putting year end adjustments into quarterly updates. They are not needed there and belong in the year end process.
• Not reconciling the bank. Regular bank reconciliation is how most duplicates and omissions are caught.
• Skipping an update because the figures are not perfect. Send it on time and correct afterwards. A nil period still needs an update.
• Weak records. If you are unsure what counts as a digital record, read MTD digital records explained.

How we can help

We review your digital records each quarter, correct errors at source, submit your updates and prepare the year end submission, so that the figures HMRC ends up with are right. Our MTD compliance service starts from £49 per month on a fixed fee. See our pricing, or contact us before your next update is due on 7 November.