The Final Declaration: MTD ITSA’s replacement for Self Assessment

For clients in scope of Making Tax Digital for Income Tax, the annual Self Assessment return has been replaced by a Final Declaration. The legal framework is the Income Tax (Digital Requirements) Regulations 2021, as amended; HMRC’s operational guidance lives in the MTD Manual. This guide covers what the Final Declaration actually is, what it pulls in, the year-end adjustments only it can carry, and how the deadline and amendment rules differ from the TMA 1970 regime firms have been working under for the last quarter-century.

What the Final Declaration is — and isn’t

The Final Declaration is the end-of-year crystallisation step. It is not a fifth quarterly update, and it is not a separate return for non-property income. It is the single, binding statement that this is the client’s income tax position for the year, taking everything in scope of MTD and everything outside it and consolidating to a tax liability under Part 2 of ITA 2007.

Two things follow from that. First, the four quarterly updates that preceded it are working figures — they don’t fix anything in law. Second, the Final Declaration is the only point in the cycle at which the full income-tax calculation actually happens. Quarterly updates are summaries of categorised transactions for the property (or trade) business; they do not apply personal allowances, finance cost restrictions, or any cross-source set-offs.

What gets pulled in

The Final Declaration consolidates three streams:

1. The four quarterly updates, with adjustments

Each quarterly submission feeds in as a categorised total per property business. The Final Declaration is also where you make any adjustments to the figures previously submitted quarterly — a misposted transaction, a late-arriving invoice, a recategorisation. Crucially, under MTD ITSA you do not file a separate amended Q2 update if you spot a mistake in November while preparing year-end; the correction is applied at the Final Declaration and forms part of the year-end numbers. This is a meaningful procedural shift from the s.9ZA TMA 1970 amendment regime, where an SA return could be amended in-year within a twelve-month window. The mechanism now is forward-correction at year-end, not retrospective amendment of an interim filing.

2. Income outside MTD

Anything not within the trade or property update flows in at the Final Declaration:

• employment income and benefits (PAYE);
• UK and foreign bank interest;
• dividends from UK and overseas companies;
• pension income, including state pension;
• chargeable gains (CGT remains on its own schedule but the income tax position must reconcile);
• other taxable receipts — trust income, partnership shares of profit, casual income.

For practical purposes this is the same set of schedules a firm would historically have populated on pages SA101 through SA110. What has changed is the timing and the source: HMRC’s pre-population services now feed PAYE and some interest figures into the Final Declaration directly, and firms should reconcile rather than re-enter.

3. Year-end adjustments and reliefs

This is the work the quarterly cycle deliberately doesn’t attempt. Items that can only be settled at year-end include:

• the Section 24 finance cost restriction on residential mortgage interest, which is applied as a basic- rate tax reducer rather than a deduction from rental profit;
• capital allowances on qualifying expenditure (notably for furnished holiday lets, where the regime still differs from other property businesses);
• replacement of domestic items relief where claims straddle quarters;
• property and rental loss treatment under ITA 2007 — carry-forward against future profits of the same property business, with no sideways relief for ordinary residential lettings;
• marriage allowance transfers, blind person’s allowance, and other personal-circumstance reliefs;
• gift aid extension of basic-rate band and pension contributions paid net of basic rate;
• the £1,000 property allowance election where the client elects to use it instead of actual expenses.

Deadline, payment, and amendment rules

The Final Declaration is due by 31 January following the end of the tax year. That mirrors the old SA filing deadline by design — for a 2026/27 Final Declaration, the date is 31 January 2028. Tax payment dates are also unchanged: balancing payment on 31 January, payments on account on 31 January and 31 July.

The amendment window after submission is twelve months from the statutory filing date, carried over from the TMA 1970 framework (s.9ZA in spirit, with the digital regulations supplying the procedural mechanics). HMRC retains a longer discovery window for negligent or careless returns. Practically, the year-end correction shift means firms tend to amend Final Declarations less than they amended SA returns: most slippage is caught during year-end review rather than in the months after filing.

Worked example: a landlord-plus-PAYE client

Take Priya: she has a £60,000 PAYE salary and lets two London flats jointly held with her husband (50/50, no Form 17 election). Across 2026/27 her share of gross rents is £42,000 and her share of allowable expenses is £8,000. She also pays £14,000 of residential mortgage interest on her share. She earned £1,200 of UK bank interest and £600 of dividends.

The four quarterly updates for her property business will have reported, in aggregate, rental income of £42,000 and allowable expenses of £8,000 — note the mortgage interest is not in the quarterly figures because s.24 restricts it to a basic-rate reducer at year-end. Property profit carried into the Final Declaration is therefore £34,000.

At the Final Declaration the firm consolidates:

• employment income (PAYE): £60,000;
• property profit: £34,000;
• savings interest: £1,200;
• dividends: £600.

Total income: £95,800. Personal allowance £12,570 is restricted to nil because adjusted net income exceeds £125,140? — no, in this example it does not, so the allowance is fully available. Tax is computed at the marginal rates. Priya is a higher-rate taxpayer. The s.24 reducer is then applied: 20% × £14,000 = £2,800 off her tax liability. PAYE tax already collected at source is credited. The resulting balance is settled on 31 January 2028, with payments on account for 2027/28 calculated and due on the same date and on 31 July 2028.

Note what the Final Declaration did that the quarterly updates could not: it applied the s.24 restriction; it brought in employment, interest and dividend income; it applied the personal allowance and the dividend and savings allowances; and it produced a single binding number for the year.

What this changes for firms

The Final Declaration is procedurally simpler than the old SA return, but only if the quarterly updates have been kept clean. The substantive complexity — s.24, capital allowances, loss treatment, joint property income under Form 17 rules, reliefs and allowances — all sits at year-end exactly as it did before. What has changed is that you no longer wait until 30 January to find out the bank feed was misclassifying something: the quarterly cycle surfaces it earlier.

The risk firms tell us about is the opposite of what they expected. Year-end isn’t lighter because the quarterly updates carried part of the load; it’s heavier because the firm now has four quarters of figures to reconcile against, plus everything outside MTD, plus all the same year-end adjustments, plus a tighter window for client follow-up because the deadline hasn’t moved.

The right intake engine for Final Declaration season is the same one that ran the quarterly cycle: continuous categorisation, continuous missing-information chase, and clean handoff to the firm’s tax software. That’s what Otto is built to do.