Sending your final declaration (replaces Self Assessment)
Once all four quarterly updates are in, the final declaration confirms your year's figures with HMRC. Under MTD, it replaces the old Self Assessment tax return.
Under Making Tax Digital for Income Tax, the final declaration takes the place of the old Self Assessment tax return. It's a single end-of-year step where you confirm your figures, HMRC calculates the tax you owe, and you sign off the year. This guide walks through exactly what happens in Keepr when you send it.
What the final declaration is, and when it's due
Across the tax year you send HMRC four quarterly updates with your business income and expenses. The final declaration is the fifth and last step: it tells HMRC "these figures are now final", lets HMRC work out your income tax and National Insurance, and locks the year's records as the official digital record. It's the equivalent of pressing Submit on the old Self Assessment return.
The deadline is 31 January following the end of the tax year - identical to the old Self Assessment deadline. So for the 2026-27 tax year (6 April 2026 to 5 April 2027), the final declaration is due by 31 January 2028. Any tax owed is due on the same date.
Before you start: prerequisites
- All four quarterly updates for the tax year must be submitted. The final declaration option only appears once Q1, Q2, Q3 and Q4 are all marked Submitted on your MTD page.
- Your HMRC connection must still be active. If it's expired, reconnect from the same page before you start.
- Anything else that needs to feed into the year - pension contributions, Gift Aid, UK savings interest, employment income, dividends - should be entered in the More tax options section first, so HMRC has the full picture before it calculates.
Step 1 - Optional adjustments
Once all four quarters are in, the MTD page shows an End of year - your steps before final declaration section with three numbered cards. The first two are optional:
Annual adjustments covers the £1,000 trading allowance, capital allowances on big equipment, and similar adjustments that don't fit into quarterly numbers. Most sole traders on cash basis either claim the trading allowance or leave this blank. Brought-forward losses lets you record a loss to carry forward against future tax. Skip either step if it doesn't apply.
Step 2 - Calculate your tax
When you're ready, click Calculate My Tax in step 3 (or in the blue hero card at the top of the page). Keepr sends a request to HMRC asking it to calculate your tax based on everything submitted so far. A brief spinner appears while HMRC works.
After a few seconds you'll see a five-row table:
| Line | What it means |
|---|---|
| Total income | Your total taxable income for the year from all sources HMRC has on file. |
| Income Tax | Tax calculated against the bands - Personal Allowance, basic, higher and additional rate. |
| National Insurance (Class 2) | Flat-rate weekly NI for self-employed people. |
| National Insurance (Class 4) | Profit-based NI on self-employment earnings above the threshold. |
| Total tax due | The total you'll need to pay HMRC by 31 January. |
Step 3 - Read the declaration and confirm
Below the figures is the legal statement HMRC requires you to read and agree to before submitting. The exact wording is:
Tick I have read and agree to the above statement to unlock the Confirm & Submit to HMRC button, then click it to send the declaration. The page reloads and the hero card switches to confirm that your tax is now filed.
What happens after you submit
- HMRC officially closes the tax year.
- Keepr locks every income and expense record dated within the tax year (6 April to 5 April) as part of the digital record. The data stays visible; you can't edit it without using the Amend Declaration flow.
- Pay any tax owed on the HMRC website by 31 January - Keepr doesn't take the payment. If you later spot a mistake, click Amend Declaration on the MTD page to recalculate and resubmit.