The short answer
Under Making Tax Digital you submit your tax return through your software by 31 January after the tax year ends. HMRC calls it the final declaration. In SimpleTaxFlow, open Tax, choose Open year-end steps and work down the list. Then choose Review your tax return, choose Calculate tax return, check HMRC’s figures, if needed unlock your filing on Stripe Checkout, then tick the declaration and choose Submit tax return.
Is this the right guide?
Use this guide once the tax year has ended and you are ready to finish it. It takes you from your last quarterly update to a submitted tax return.
If you already submitted and need to change something, use the guide to correcting a submitted tax return instead.
The MTD tax return in brief
Your tax return confirms your income for the whole tax year. It is due by 31 January after the tax year ends, and you can submit it earlier. Your first Making Tax Digital tax return, for 2026 to 2027, is due by 31 January 2028. The 2025 to 2026 return is still a normal Self Assessment return, due by 31 January 2027.
You must send all your quarterly updates for the year before you can submit. You must also add other income, such as savings interest and dividends, before you submit. HMRC adds some information for you, such as PAYE pay and CIS deductions.
Making Tax Digital does not change how you pay or when payments are due. Submitting does not pay your tax. You cannot claim a tax refund in your tax return using Making Tax Digital. Ask for a refund through your HMRC online account.
What you need
- All quarterly updates HMRC requires for each business sent, including a ceased business’s remaining periods.
- Any allowances, adjustments or losses you want to claim.
- Your P60, savings interest statements and dividend vouchers, if you have that income.
- Time to read HMRC’s calculation before you tick the declaration.
1. Open year-end steps
Open Tax. In the End of year card, choose Open year-end steps. The Year-end tax return panel lists each step in order.
Open Tax2. Fix records
Choose Review records to check the records behind your figures. Receipts are optional.
Review records3. Resend Q4 if changed
If you corrected anything after your fourth quarterly update, open that business’s final update and send the corrected figures. If no final update shows, sync HMRC first.
Open Tax4. Allowances, adjustments and losses
Use Allowances, Adjustments and Losses and claims for anything that applies to you. Many people need none of them.
Make year-end adjustments5. Other income
Choose Review other income to add savings interest, dividends or CIS deductions. If you have income SimpleTaxFlow does not support, such as capital gains or foreign income other than dividends, the year-end steps tell you. You then need other MTD software for your tax return.
Add other income6. Check HMRC’s calculation
Choose Open calculation. Read HMRC’s figures and the disclaimer. Your set-aside figure is our estimate. HMRC’s calculation is the one your tax return uses.
Understand the calculation7. Calculate your tax return
Choose Review your tax return. Clear any record, adjustment or eligibility blockers in the Pre-submission checklist. Reminders in the checklist come from your last HMRC refresh. They do not stop you calculating. Choose Calculate tax return. We check HMRC’s current obligations for every business before requesting the calculation. If Quarterly updates still to send appears, send the named business periods and calculate again. If Calculation pending appears, wait a minute, then choose Calculate tax return again. If you see No submissions found, check that you have sent your quarterly updates for the tax year. HMRC returns Total liability, Income tax, NIC2 and NIC4. If HMRC flags calculation errors, fix them before you submit.
Open your tax return8. Confirm the declaration and submit
If you need a plan, choose Unlock and submit, then the annual or monthly plan. Pay on Stripe Checkout in the same tab. On return, wait for confirmation. Your reviewed calculation is kept. Read HMRC’s declaration and tick the box. Choose Submit tax return. Payment never submits the return. You see Tax return submitted with a reference. Keep it.
Open your tax return9. Pay
Submitting does not pay your tax. Check HMRC for the amount and the payment date, then pay HMRC directly.
Pay Self AssessmentA worked example
Casey (fictional) is a self-employed gardener who also has a savings account. Casey sends the fourth quarterly update in April 2027 and has nothing to correct, so there is no need to resend it.
Casey adds the savings interest under Review other income, opens HMRC’s calculation, then chooses Review your tax return and Calculate tax return. Casey checks the figures against the year’s records, ticks the declaration and chooses Submit tax return in June 2027, well before the deadline.
- Turnover from quarterly updates
- £36,000
- Expenses from quarterly updates
- £8,000
- Profit
- £28,000
- Untaxed savings interest added at year end
- £300
- Tax return deadline
- 31 January 2028
HMRC’s calculation shows the tax. Casey checks the HMRC online account for what to pay and when.
Common mistakes
- Submitting before resending a corrected fourth quarterly update.
- Forgetting savings interest or dividends because they are not in the quarterly updates.
- Treating our set-aside estimate as HMRC’s figure. HMRC’s calculation is the one that counts.
- Thinking that submitting the tax return also pays the tax.
- Leaving it until the last days of January, when any problem leaves no time to fix it.
How to check it worked
After you submit, you see Tax return submitted with an HMRC reference. In the year-end steps, Declare and submit your tax return shows as done. Under More, Submission history lists the tax return. Choose Open receipt or Download, then PDF receipt, to keep a copy.
Then sign in to your HMRC online account to see what you owe and when.
Before you move on
- All quarterly updates for the year are sent
- Allowances, adjustments, losses and other income are added where they apply
- HMRC’s calculation was checked before submitting
- HMRC’s declaration was read and ticked
- £30.00 + VAT a year or £3.50 + VAT a month. Bookkeeping is free. Pay when you send to HMRC.
Frequently asked questions
What is the final declaration?
It is HMRC’s name for the Making Tax Digital tax return. It confirms your income for the whole tax year. SimpleTaxFlow calls it your tax return.
When is the MTD tax return due?
By 31 January after the tax year ends. For example, the return for the year ending 5 April 2027 is due by 31 January 2028. You can submit it earlier.
Can I change my tax return after I submit it?
Yes, within 12 months of the 31 January deadline. Open your tax return and choose Start amendment.
Do I have to send all four quarterly updates first?
Yes. HMRC says the updates must still be sent before you can submit your tax return, even for 2026 to 2027 when there are no penalties for late updates.
Does submitting my tax return pay my tax?
No. Submitting tells HMRC your figures. You pay HMRC separately, by the usual Self Assessment dates, which Making Tax Digital does not change.
Check the official rules
Tax rules can change and individual circumstances matter. Use HMRC’s current guidance to confirm the treatment that applies to you.
Put the guide into practice.
Open the relevant workspace and complete the next step with this guide available in another tab.
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