MTD ITSA Quarterly Reporting: Avoid Common Data Errors

MTD ITSA Is Now Live: Are Your Submissions Accurate?

Since April 2026, sole traders and freelancers earning over £50,000 annually have been required to submit quarterly updates to HMRC through MTD ITSA-compatible software. If you are already in the system, you will know that each quarter you must report your business income and expenses digitally. What many users are discovering, however, is that small data errors can cause significant headaches further down the line.

The Most Common Submission Errors to Watch For

Based on early experience with the new regime, the following mistakes are appearing most frequently:

• Mixing personal and business expenses: One of the biggest errors is including personal costs within business expense categories. HMRC's digital records requirements mean every transaction must be clearly categorised. A meal with a friend is not a business entertainment expense, even if it was loosely work-related.
• Incorrect income categorisation: If you have multiple income streams, each must be reported under the correct property or self-employment business. Mixing rental income with freelance income in a single return will cause reconciliation problems at year end.
• Duplicate entries from bank feeds: Many MTD-compatible software packages use automated bank feeds. If you also enter transactions manually, you risk duplicating entries. Always check your transaction list before submitting a quarterly update.
• Missing or late quarterly deadlines: The four quarterly deadlines fall on 7 August, 7 November, 7 February, and 7 May each year. Missing a deadline triggers a points-based penalty under the new HMRC system, where accumulating four points results in a £200 fine.
• Submitting nil returns incorrectly: If you had no income or expenses in a quarter, you still need to submit a return. Leaving a quarter blank or failing to submit at all is treated as a missed filing, not a zero return.

How to Clean Up Your Data Before Each Submission

Good habits before you hit submit will save you from corrections and amendments later. Follow this simple pre-submission checklist:

• Reconcile your software records against your bank statement for the quarter before submitting.
• Review all expense categories to ensure they align with HMRC's allowable business expenses guidance.
• Check that all income entries match actual invoices raised or payments received during the quarter.
• Remove any duplicate transactions created by automatic bank feeds or manual entries.
• Confirm you are submitting under the correct business or property income source if you have more than one.

Understanding What Quarterly Updates Actually Contain

It is worth clarifying what a quarterly update is and is not. Under MTD ITSA, your quarterly submissions report cumulative totals of income and expenses for each business. They are not your final tax return. You are not paying tax at the quarterly stage. The End of Period Statement (EOPS) and your final declaration, due by 31 January following the tax year, are where your actual tax liability is confirmed. This means errors in quarterly data do not automatically result in the wrong tax bill, but they do create a confusing paper trail that takes time to unravel.

Use Software That Works for You

HMRC maintains a list of MTD ITSA-compatible software products. Choose one that offers bank feed reconciliation, automatic expense categorisation, and built-in submission checks. EasyTax integrates directly with HMRC's API, flags potential categorisation errors before submission, and sends you deadline reminders so you never miss a quarterly window.

When to Speak to an Accountant

If you have multiple income sources, recently started trading, or are unsure how to categorise certain expenses, it is worth speaking to a qualified accountant before your next quarterly deadline. Getting it right from the start is far less costly than correcting a year's worth of misallocated transactions ahead of your final declaration.