MTD Quarter 1 — What If You Made a Mistake? How to Correct Your Submission
By RentVault Team · Published 2026-07-21 · 5 min read
The deadline for your first MTD quarterly submission is 7 August 2026. Many landlords will submit on time, review their figures afterwards, and realise something is wrong.
The deadline for your first MTD quarterly submission is 7 August 2026. Many landlords will submit on time, review their figures afterwards, and realise something is wrong. A forgotten expense, a miscategorised item, a transaction from Airbnb that was missed.
The good news is that HMRC expects this. Quarterly updates are estimates — corrections are part of how the system is designed to work. Here is exactly what to do if you spot a mistake in your Quarter 1 submission.
Why corrections are expected
HMRC's official position on MTD quarterly updates is that they are not the final picture. They are estimates of your income and expenses for the quarter, which will be reconciled against your actual figures at the end of the tax year. You are not required to have every receipt perfectly categorised before you submit.
This means that a correction to a quarterly update is not an admission of wrongdoing. It is using the system as designed.
The grace period in 2026/27
An important point for the 2026/27 tax year specifically: HMRC will not issue penalty points for late quarterly updates this year. The 2026/27 tax year is effectively a soft-landing year for MTD. Penalties for late quarterly submissions begin from April 2027.
This means that if you missed the 7 August deadline entirely, or submitted something that needs substantial correction, the consequences in 2026/27 are less severe than they will be from next year. Use this year to build the habit and get your record-keeping system right — but do not ignore the obligations entirely. The late submission still needs to be made.
How to correct a Quarter 1 submission
If you submitted your Quarter 1 update and have since identified an error, you can submit an amended update for the same period. Most MTD-compatible software — including RentVault — allows you to generate and submit a revised quarterly update for a period that has already been submitted.
The process is:
- Identify the error and correct your records. Update the transaction or category that was wrong.
- Generate a new quarterly update from your corrected records for the Quarter 1 period (6 April to 5 July 2026).
- Submit the amended update to HMRC through your software. The amended figures replace the original submission.
You do not need to notify HMRC separately that you are making a correction. Submitting the amended update is sufficient.
Common Quarter 1 errors and how to fix them
Mortgage capital repayments included in finance costs. Only the interest portion of your mortgage payment qualifies as a finance cost. If your mortgage payment includes a capital repayment element and you included the full payment, your finance costs figure will be too high. Correct it by recalculating using only the interest element — your lender's mortgage statement will show the split.
Mortgage interest included in expenses rather than finance costs. These are separate fields in your MTD submission. Mortgage interest must go in the Finance Costs field to generate the 20% tax credit. If you put it in an expense category, you will not receive the correct relief.
Missing Airbnb or short-let platform income. All income from short-let platforms must be included. The gross income (before platform fees) is your income, and the platform fees are an allowable expense. If you only declared the net amount paid out by the platform, both your income and your expense figures are understated.
Wrong expense category. If you put a cost in the wrong category — for example, putting insurance in the repairs field — this does not affect the total expense deduction but may flag as unusual if your figures are reviewed. Correcting the category is worth doing even though the bottom line does not change.
Capital improvement included as a repair. If you included the cost of an improvement — work that left the property in a materially better condition than before — in your repairs and maintenance field, you need to remove it. Capital costs are not allowable expenses and do not belong in your quarterly submission at all.
Forgotten transaction from early in the quarter. April and May transactions can sometimes be missed, particularly if you are pulling records manually. The correction is to add the transaction to your records and resubmit.
Should you correct before or after the 7 August deadline
If you have already submitted and spotted an error before 7 August, you can correct and resubmit before the deadline. This is the cleanest approach.
If you spot the error after 7 August, correct and resubmit as soon as you can. There is no fixed deadline for corrections to quarterly updates — they can be made at any point before the year-end End of Period Statement.
What about errors that affect previous tax years
Quarter 1 of 2026/27 only covers the period from 6 April 2026. If you have identified an error that relates to the 2025/26 tax year (before 6 April 2026), that is a separate matter. Errors in previous years are corrected through your self-assessment tax return for that year or by contacting HMRC directly. Your accountant can advise on the right approach.
Getting your records right before Quarter 2
The most useful thing you can do after submitting Quarter 1 — corrected or not — is to set up a record-keeping system that prevents the same issues in Quarter 2. The Quarter 2 period runs from 6 July to 5 October 2026, with a submission deadline of 7 November 2026.
If you are using RentVault with a bank feed connected, transactions are pulled directly from your bank account and flagged for categorisation. Keeping your categorisation current throughout the quarter — rather than reconstructing it at submission time — makes each subsequent submission a much simpler process.