A Roadmap to the MTD Year-End Process: What Agents Need to Know

MTD is becoming mandatory from April 2026 for individuals with qualifying income over £50,000. What do you need to know?

Introduction

With Making Tax Digital for Income Tax (MTD ITSA) becoming mandatory from April 2026 for individuals with qualifying income over £50,000, many agents and accountants are seeking clarity on how the end-of-year process will differ from traditional Self‑Assessment. New HMRC guidance, backed by updated Professional Conduct in Relation to Taxation (PCRT) guidance, now sheds light on precisely that.

What Is the MTD Year‑End Filing?

Although often referred to as a “final declaration” or “digital return,” the formal term retained by HMRC is simply “tax return”—but in this context, it’s an “MTD tax return”, distinct from the current Self‑Assessment filing process.

Why the New Name?

• Clarifies that this replaces the current paper or digital Self‑Assessment return.

• Highlights the software-driven process under MTD.

Five Key Steps Agents Must Handle

MTD year-end actually consists of five critical steps, all taking place within compatible software:

1. Trading & Property Adjustments — Pull the results from the fourth quarterly update into tax software, and apply accounting or tax adjustments where needed. No re-entry required.

2. Adding Other Income & Gains — Income such as PAYE, pension, CIS deductions, and property gains will typically be pre‑populated from HMRC. Income not held by HMRC (e.g. dividends, savings interest, capital gains) must be manually entered.

3. Triggering the Tax Calculation — Once adjusted data is entered, the client’s image of tax liability is calculated via HMRC’s systems. This step doesn’t declare or submit—yet—but allows review of preliminary figures.

4. Reviewing & Adjusting — If the modelled calculation appears wrong, check data inputs, correct as needed, and re-trigger until it aligns with expectations.

5. Final Submission — With client approval secured, agents make the final declaration—confirming information is complete and correct—and officially file the return.

Client Sign‑Off: What You Need to Know

PCRT guidance has been updated to advise that only the final return and related calculation require formal client approval. Earlier steps—such as triggering a calculation—do not, as they hold no legal standing. This resolves earlier uncertainty over multiple rounds of client sign‑off and reinforces that only the final filing step carries formal risk and legal obligation.

Final Takeaways for Agents

• Familiarise yourself with software workflows, particularly how quarterly updates feed into year-end returns and where to apply client-sourced adjustments.

• Request demos or trials from your software provider to verify end-to-end functionality.

• Begin preparing clients well in advance—explaining that year-end is a software process not a manual exercise.

• Develop clear internal protocols for capturing client approval before final declaration submissions.

Why It Matters to AIR & Its Audience

Your readership—accountants and tax agents—will benefit from clear, actionable guidance on tasks they are soon required to perform. This roadmap article unpacks not only the steps involved in MTD compliance, but also practical timing and software integration considerations.