How to File Your Final Declaration

The final declaration is the last step in your MTD tax year. It replaces the Self Assessment tax return: you confirm your figures for the year, review HMRC's tax calculation and formally declare your income. For the 2026-27 tax year the deadline is 31 January 2028.

Before you start

• All four quarterly updates are submitted for every business. The Complete Final Declaration card appears on your dashboard once they are, and the tax year has ended.
• You know about your other income. Affordable MTD only reports self-employment and UK property income. Anything else (salary, dividends, interest, pensions, capital gains, foreign income) needs to be reported through your HMRC online account before you declare.
• Optional: annual adjustments and losses. You can add these from the dashboard beforehand, or during the wizard. See Annual Allowances and Adjustments.

Step-by-step: the final declaration wizard

Click Complete Final Declaration on your dashboard. The wizard has seven steps, shown along the top of the screen. Click Continue to move between them. Your progress is saved as you go.

1. Other income

Your final declaration must cover all your income for the tax year, not just self-employment and property. If you had any of the following, report it in your HMRC online account first (the step links straight there):

• Employment income (PAYE)
• Dividends
• Savings and interest
• Pensions
• Capital gains
• State benefits
• Foreign income
• Other taxable income

Then tick the box to confirm you've reported all your other income, or that you have none. If you're not sure, use GOV.UK's check if you need to tell HMRC about additional income tool.

2. Periods of account

For each self-employment business, confirm your accounting period for the year and click Save periods of account. Most sole traders have a single period covering the full tax year. If you only have UK property income, there's nothing to do here.

3. Allowances

Review your annual allowances and adjustments, such as the Annual Investment Allowance or the Trading Income Allowance. Each business shows whether claims have been added, with Add claims or Review / Edit. If you have nothing to claim, tick the box to confirm and continue. Our annual adjustments guide explains each field.

4. Review summaries

HMRC builds a summary of each business's income and expenses for the year from your quarterly updates. Check it carefully:

• If it's right, click Confirm — no corrections needed.
• If something needs changing, click Make corrections. Each field shows the figure from your quarterly updates. Change it to what it should be, and Affordable MTD works out the adjustment for HMRC. Only fields you change are submitted.

Landlords: residential finance costs (mortgage interest) can't be changed here. HMRC uses the figures from your quarterly updates; to change them, amend your Q4 quarterly update.

5. Losses

If your business made a loss in an earlier year, click Manage losses to bring it forward against this year's profit, or to claim sideways relief against other income. Most people can skip this: tick the box to confirm you have no losses to report.

6. Review

You'll see HMRC's tax calculation for the year, including your Income Tax and Class 4 National Insurance, and any feedback HMRC has on your figures. Read any HMRC feedback and acknowledge it, then tick the box to confirm you understand the figures are an estimate based on what HMRC currently holds.

If anything looks wrong, go back and fix it before you declare.

7. Declare

Read the declaration and tick the box to confirm that the information you've submitted is correct and complete. Then click Submit final declaration.

You'll see a confirmation with the date and time of submission.

Paying your tax

If you owe tax, pay it by 31 January following the end of the tax year (31 January 2028 for 2026-27). You pay HMRC directly: Affordable MTD handles the filing, not the payment. You can pay through your HMRC online account by bank transfer, debit card or Direct Debit. Late payment penalties start 15 days after the deadline, and interest is charged from the day after.

Amending your final declaration

You can amend a submitted final declaration for up to 12 months after the filing deadline (until 31 January 2029 for the 2026-27 tax year). After submitting, your final declaration page shows a Need to make changes? section:

• Use Amend quarterly updates if you need to correct your quarterly figures first.
• Then click Submit amended return. You go through the same steps again, ending with Confirm amendment instead of Declare.

Key deadlines for 2026-27

• Tax year ends: 5 April 2027
• Q4 quarterly update due: 7 May 2027
• Final declaration and payment due: 31 January 2028
• Last date to amend: 31 January 2029

Frequently asked questions

Does the final declaration replace Self Assessment?

Yes. Once you're in MTD, the final declaration is your tax return. It covers all your income for the year. Affordable MTD submits it for your self-employment and UK property income; you report any other income through your HMRC online account before you declare.

Can my accountant file the final declaration for me?

Yes. If your accountant is authorised as your agent, they can submit it on your behalf using their own MTD software.

What happens if I miss the deadline?

A late final declaration earns a penalty point under HMRC's points system, and this applies from the 2026-27 tax year. At 4 points you get a £200 penalty. Late payment penalties and interest apply separately. See our penalties guide.