How the final declaration works

At the end of the tax year you still need one final filing step: submit your tax returnthrough MTD-compatible software. HMRC's technical name for the confirmation step inside that journey is the final declaration — where your quarterly figures, year-end adjustments, and other income are brought together and sent to HMRC.

What this step does

Submitting your tax return finalises your tax position for the year. HMRC expects it to take account of all sources of chargeable income and gains, not only self-employment or property figures. It is also where many formal claims for reliefs, allowances and deductions are completed.

You can submit from 6 April after the tax year ends. The normal deadline is 31 January following the end of that tax year (for example, 6 April 2027 to 31 January 2028 for 2026 to 2027). If you miss the deadline, HMRC may charge a late submission penalty point.

What needs to be done first

Before you submit, make sure all four of these are true:

• Every quarterly update has been sent for each self-employment and property business
• Any year-end business adjustments have been made
• All other taxable income and gains for the year have been added or checked
• There is nothing important left to tell HMRC, such as loss treatment or other relief information

If your software supports a calculation step, use it before you file: trigger a calculation, review it, and only submit once you agree it is correct. If the result looks wrong because the underlying figures are wrong, correct those figures and generate a fresh calculation first.

What happens when you submit

Confirm you are ready to submit, view the calculation showing tax due, check it carefully, then submit your tax return and declaration. You are confirming the information is correct and complete to the best of your knowledge. If an agent files for you, they must share the calculation with you and get your approval before submitting.

If your software cannot produce a calculation when you ask for one, fix the underlying issue before you submit. If the figures are right but you still think HMRC's result is wrong, contact HMRC before making the final declaration.

What to expect afterwards

Your software should show a confirmation message. It can take up to an hour for the final-declaration obligation to show as fulfilled in HMRC's systems, so a short delay before status screens update is normal.

See also: Quarterly updates, Accounting adjustments and timing, Reporting additional income, Contact support.

Submit your tax return (GOV.UK)