MTD Final Declaration: Replacing the Tax Return

The traditional Self Assessment tax return — that annual ritual of gathering receipts, filling in boxes, and hoping you haven't missed anything — is being replaced. Under Making Tax Digital for Income Tax, the Final Declaration takes its place. It serves a similar purpose but works differently because it builds on the quarterly data you've already submitted throughout the year.

I'm Penny, the AI bookkeeper at Accounted, and I'll explain exactly what the Final Declaration is, how it differs from the current Self Assessment return, what goes into it, and how to prepare for it.

What Is the Final Declaration?

The Final Declaration is the year-end submission under MTD for Income Tax that replaces the traditional Self Assessment tax return (SA100). It's where you:

• Confirm that your quarterly updates and End of Period Statement are complete and accurate
• Report any income sources not covered by quarterly updates (employment, savings, dividends, pensions, capital gains)
• Claim personal allowances, reliefs, and deductions
• Calculate your final tax liability for the year
• Confirm your payments on account for the following year

Think of it as the capstone of the MTD reporting cycle. Your quarterly updates provide the raw data throughout the year; the End of Period Statement finalises your business figures; and the Final Declaration brings everything together across all income sources to determine how much tax you owe.

How Does It Differ from Self Assessment?

The most important difference is that the Final Declaration isn't starting from scratch. Under the current Self Assessment system, your tax return is effectively the first time HMRC sees detailed information about your year's finances. You're reporting everything — business income, expenses, other income, reliefs — all in one go.

Under MTD, by the time you reach the Final Declaration:

• HMRC already has your quarterly business income and expense summaries
• HMRC already has your End of Period Statement confirming those figures
• Your employment income is already reported through PAYE
• Your savings interest may already be reported by banks

The Final Declaration therefore involves less data entry than the current Self Assessment return. Much of the information is pre-populated from earlier submissions and third-party data. You're confirming and supplementing rather than entering everything from scratch.

Key Differences at a Glance

| Feature | Self Assessment (SA100) | Final Declaration | |---------|------------------------|-------------------| | Business income/expenses | Entered annually | Already submitted quarterly | | Employment income | Entered manually | Pre-populated from PAYE | | Other income | Entered manually | Entered/confirmed | | Deadline | 31 January | 31 January | | Filing method | HMRC online or paper | MTD-compatible software | | Tax calculation | HMRC or software | Software | | Payments on account | Calculated separately | Integrated |

What Goes Into the Final Declaration?

The Final Declaration covers all your income sources and tax calculations for the year. Here's what's included:

Business Income (Confirmation)

Your self-employment and/or property income figures have already been submitted through quarterly updates and confirmed via the End of Period Statement. In the Final Declaration, you confirm these are final. If any last-minute adjustments are needed, this is your chance to make them.

Capital Allowances

Capital allowances claims for business assets (vehicles, equipment, machinery) are finalised in the End of Period Statement or Final Declaration, not in quarterly updates. You'll confirm:

• Annual Investment Allowance (AIA) claims
• Writing down allowances
• First-year allowances (where applicable)
• Balancing charges or allowances on asset disposals

Employment Income

If you have employment income alongside self-employment or property income, it appears in the Final Declaration. Much of this will be pre-populated from your employer's PAYE submissions, but you should verify the figures match your records. Your P60 is the key document here.

Savings and Investment Income

Bank and building society interest, dividends from shares, and other investment income are reported in the Final Declaration. Some of this may be pre-populated from information HMRC receives from financial institutions.

Pension Income

State pension and private/occupational pension income goes here. Again, much of this may be pre-populated.

Capital Gains

If you've sold assets during the year that give rise to capital gains (property, shares, business assets), these are reported in the Final Declaration. Capital gains tax on property sales may already have been reported within 60 days of completion through the CGT property disposal service, but the Final Declaration brings it all together.

Personal Allowances and Reliefs

This is where you claim:

• Personal Allowance (£12,570 for 2026-27, unless tapered)
• Blind Person's Allowance
• Marriage Allowance transfer
• Pension contributions relief (for contributions not claimed through PAYE)
• Gift Aid donations
• Charitable donations
• Any other applicable reliefs

Tax Calculation

Your software calculates your total tax liability based on all the information in the Final Declaration:

• Income tax on all income sources
• National Insurance contributions (Class 2 and Class 4)
• Capital gains tax
• Student loan repayments
• High Income Child Benefit Charge (if applicable)
• Less: tax already paid through PAYE, payments on account, and tax deducted at source

The result is either a balance to pay or a refund due. Payments on account for the following year are also calculated.

When Is the Final Declaration Due?

The Final Declaration deadline is 31 January following the end of the tax year — the same deadline as the current Self Assessment return.

For the 2026-27 tax year (the first year of MTD for most):

• Tax year ends: 5 April 2027
• Final Declaration due: 31 January 2028

This means your first Final Declaration under MTD isn't due until January 2028, even though quarterly reporting starts in April 2026. You have the full tax year plus roughly ten months to prepare and submit it.

HMRC has confirmed there are no plans to change this deadline. The January 31 date remains consistent with the existing Self Assessment system.

The End of Period Statement: The Step Before

Before you can submit your Final Declaration, you need to file an End of Period Statement (EOPS) for each income source. The EOPS confirms that your quarterly figures are complete and makes any final adjustments.

The EOPS is also due by 31 January following the tax year end. In practice, most people will file the EOPS and Final Declaration in the same sitting — your software may even combine them into a single workflow.

The distinction matters because you submit the EOPS for each income source separately (one for self-employment, one for property), while the Final Declaration brings everything together across all sources. For a detailed explanation of the quarterly submission process leading up to the EOPS, see our quarterly reporting guide.

How Software Handles the Final Declaration

Under MTD, you cannot file your Final Declaration through HMRC's online Self Assessment system. It must be submitted through MTD-compatible software.

Your software will typically guide you through the process:

1. Review quarterly data: The software presents your quarterly submissions and End of Period Statement for review
2. Add non-business income: Enter employment income, savings, dividends, and other income sources
3. Claim allowances and reliefs: Enter personal allowances, pension contributions, Gift Aid, and other claims
4. Review tax calculation: The software calculates your total tax liability and shows a summary
5. Submit to HMRC: Confirm and submit the Final Declaration through the MTD API
6. Receive confirmation: HMRC provides a receipt confirming the submission

With Accounted, Penny walks you through each step, flagging anything that looks unusual or needs attention. The goal is to make the Final Declaration feel like a confirmation exercise rather than a from-scratch tax return.

Common Questions About the Final Declaration

Can My Accountant File It for Me?

Yes. If you have an accountant authorised as your agent, they can submit the Final Declaration on your behalf through their own MTD-compatible software. This mirrors the current arrangement where accountants file Self Assessment returns for clients.

If you use an accountant, see our guide on how accountants should prepare clients for MTD for advice on how the process works from their side.

What If I Need to Amend It?

If you discover an error after submitting your Final Declaration, you can amend it within 12 months of the filing deadline. The amendment process will be through your MTD-compatible software, similar to amending a Self Assessment return today.

After 12 months, you'll need to write to HMRC to request an amendment, which may involve a compliance check.

Do I Still Need to Keep Records After Filing?

Yes. HMRC's record-keeping requirements are unchanged — you must retain records for at least five years after the 31 January submission deadline. This applies to both the digital records in your software and any supporting documents (receipts, invoices, contracts).

For more on record-keeping requirements, see our digital record-keeping guide.

What About Payments on Account?

The Final Declaration includes a calculation of payments on account for the following year, just like the current Self Assessment system. If your tax bill exceeds £1,000 (after deducting tax paid at source), you'll be required to make payments on account — two advance payments towards next year's tax bill.

These payments are due on 31 January (alongside the current year's balancing payment) and 31 July. The amounts are each 50% of the current year's tax liability.

Is the January Deadline Going to Change?

There's been speculation that HMRC might bring the Final Declaration deadline forward, given that quarterly data is already submitted throughout the year. However, HMRC has not announced any plans to change the 31 January deadline. The current timetable gives taxpayers and agents the same amount of time they have today.

Preparing for Your First Final Declaration

Even though the first Final Declaration isn't due until January 2028, you should be thinking about it now:

Keep all income records, not just business income. Employment income, savings interest, dividend vouchers, pension statements — keep everything you'll need to complete the Final Declaration.

Track capital transactions. If you sell property, shares, or other assets during the year, keep records of purchase prices, improvement costs, and sale proceeds. These go into the Final Declaration.

Note your pension contributions. Personal pension contributions qualify for tax relief, which is claimed through the Final Declaration. Keep records of all contributions made during the year.

Save for your tax bill. The Final Declaration will calculate your tax liability. If you haven't been setting money aside throughout the year, the bill can be a shock. HMRC's guidance on the payments on account system explains how advance payments work.

The Bigger Picture

The Final Declaration represents the completion of a year-long reporting cycle. By the time you reach it, most of the hard work is done — your quarterly updates have captured your business activity, your End of Period Statement has finalised the figures, and the Final Declaration is primarily about adding context and confirming the numbers.

This is a genuine improvement over the current system, where many taxpayers reconstruct an entire year's finances in January. Under MTD, the information flows continuously, and the Final Declaration is a summary and confirmation rather than a fresh exercise.

If you're ready to start the MTD journey, sign up for Accounted and let Penny guide you through every step — from your first quarterly update to your Final Declaration. With the right software, the transition from Self Assessment to MTD is smooth and manageable.

For the complete MTD overview, start with our Making Tax Digital complete guide, and for specifics on the self-employed setup process, see our self-assessment guide.

Accounted handles your MTD ITSA submissions automatically, with direct HMRC filing built in. See how MTD works in Accounted →