MTD for ITSA: What It Actually Means for Your Clients' Bookkeeping

Making Tax Digital for Income Tax Self Assessment is the most significant structural change to self assessment since it was introduced. It replaces the annual tax return with continuous digital reporting: four quarterly updates per year, an End of Period Statement, and a Final Declaration, versus one annual return previously.

The rollout is phased. Sole traders and landlords with gross income above £50,000 from April 2026. Dropping to £30,000 from April 2027. £20,000 from April 2028. For most practices, the first wave of clients is already in scope.

The quarterly deadline structure

Quarterly updates are due on fixed dates: 7 August, 7 November, 7 February, and 7 May. Missing a submission results in a penalty point. Accumulate enough points and a financial penalty is triggered. Resetting the points counter requires a period of full compliance with all returns submitted for the previous 24 months, which means a single missed quarter has consequences that last two years.

Quarterly updates are cumulative: each submission overwrites the previous one. Errors in the underlying records compound through every subsequent submission until caught. The clean-up at quarter four is much harder than getting it right at quarter one.

The bookkeeping problem

MTD-compatible software handles the submission mechanics. It cannot keep the underlying records accurate between quarters. That's a bookkeeping problem, not a software problem.

Under the old system, a client could hand over a shoebox of receipts in January. That model no longer works. Quarterly submissions require quarterly bookkeeping.

Records need to be current, reconciled, and correctly coded at each submission deadline, not assembled from memory three months later.

Property income and trading income must also be tracked separately. Where a client has both rental income and trading income, quarterly updates are required per source individually. Two separate income streams mean two separate sets of records maintained throughout the year.

What we do

We keep bookkeeping current between quarters, reconciling bank feeds, coding transactions correctly, and separating income sources so that each quarterly submission is based on accurate, up-to-date records rather than a retrospective reconstruction. We also track the quarterly deadline schedule per client and confirm agent authorisation is in place before the first submission is due for each client coming into scope.