Can an accountant submit the final declaration for sole traders and landlords?

Yes, if they are your main agent and you have authorised them. HMRC now calls the final declaration your tax return. For 2026-27 it is due by 31 January 2028, and you check and confirm it first.

Under Making Tax Digital for Income Tax (MTD), you send four quarterly updates a year and then a tax return. HMRC used to call that last step the final declaration. Its terminology guide for software developers now says not to use that term with customers and to say tax return instead, and GOV.UK's guidance does the same. This page follows GOV.UK as checked on 16 October 2026.

What the tax return does

The quarterly updates are summaries of your business or rental income and expenses. GOV.UK says they are "summaries, not tax returns". The tax return is where the year is finished. In it you, or your agent:

• make any year-end adjustments to your self-employment and property income and expenses;
• add your other income and gains. HMRC adds some information, such as pay from a job and pensions, and you add items such as savings interest and dividends;
• make most formal claims for reliefs and allowances, according to HMRC's guide for software developers;
• view and check the tax calculation;
• declare that the information is correct and complete to the best of your knowledge.

It is due by 31 January after the end of the tax year, and you can send it any time after the year ends, once your quarterly updates for the year are sent. It is sent from MTD-compatible software.

Who does what

GOV.UK lets you have one main agent and any number of supporting agents. Only the main agent can send your tax return.

What the accountant has to do

GOV.UK's guidance for agents says that before sending your return they must add all your income sources and gains, share a copy of the information with you, and ask you to confirm in writing that it is correct and complete. They then submit it by declaring that the information and calculation are correct and complete to the best of their knowledge. HMRC's software guide adds that the agent confirms you have received a copy of everything being filed.

What this means for you

An accountant can send your tax return under MTD, but only as your main agent. If you already have an accountant for Self Assessment, they can usually bring that authorisation across, and HMRC treats them as your main agent.

Two things stay with you. GOV.UK says "You are responsible for your own tax affairs, even if you authorise someone to act on your behalf." And it says you must check the information in your tax return is correct and let your agent know before they submit it. Reply to their request with time to spare before 31 January.

A late tax return earns one penalty point. At 4 points HMRC charges a £200 penalty. The 2026-27 relief from points covers missed quarterly updates only, not the tax return.

Steps to get an accountant to send it

1. Agree with the accountant that they will be your main agent, since only a main agent can send the tax return.
2. Accept their authorisation link within 21 days, or check they have brought your Self Assessment authorisation across.
3. Make sure all four quarterly updates for the year have gone, by 7 May after the year ends.
4. Give them details of any other income, such as savings interest, dividends or gains, and anything you want to claim.
5. Read the copy they send you, check the tax calculation and confirm in writing that it is correct and complete.
6. Ask them to tell you once it has been sent, and pay any tax due by 31 January. GOV.UK says MTD does not change the dates payments are due.

Dates for 2026-27 and 2027-28

Each quarterly update covers the tax year so far, from 6 April. GOV.UK says that after your final update, check whether anything needs adjusting, and resend the fourth update if needed before making tax adjustments in the return. If you find a mistake after sending the return, you can correct it in your software within 12 months of the deadline.

Not sure when you start? The free MTD check shows your date. Our own tax plans start once our HMRC registrations are complete. Until then you can join the waitlist, and no payment is taken. See the trades section or the landlord section.