Government to Implement MTD for IT With Lower £20,000 Threshold: What the Phase-3 Mandate Means for UK Landlords

If your gross rents top £20,000, you are heading into Making Tax Digital for Income Tax (MTD ITSA), and the trap most people miss is that the test is on gross income, not the profit you actually pay tax on. From 6 April 2028, landlords and self-employed taxpayers with qualifying income above £20,000 are mandated into quarterly digital reporting under the phase 3 threshold, confirmed at Spring Statement 2025 and Autumn Statement 2025. This is the biggest cohort by far: HMRC's published impact assessment estimates roughly 700,000 to 800,000 newly-mandated taxpayers at the £20,000 level, more than the phase 1 (£50,000 from 6 April 2026) and phase 2 (£30,000 from 6 April 2027) cohorts combined.

If you are in scope, the 18 to 24 months between now and the 6 April 2028 start are your runway, and you should use them. The choices you make in that window (your software, whether you pilot a voluntary opt-in, getting your accountant onto an Agent Services Account, sorting the joint-property arithmetic with your spouse, weighing up incorporation) decide whether the switch is smooth or whether your first quarterly deadline arrives in chaos.

The three-phase MTD ITSA mandate timeline

The mandate framework sits at Schedule A1 of the Finance (No. 2) Act 2017 and is operative under the Income Tax (Digital Obligations) Regulations 2026 (SI 2026/336), which revoked the earlier Income Tax (Digital Requirements) Regulations 2021 (SI 2021/1076) on 1 April 2026. Substantive mechanics carry over; the regulation numbers have migrated (qualifying income at reg 25, qualifying amount at reg 27, three-year income-exit at reg 24). The three phases:

• Phase 1: mandate from 6 April 2026 for qualifying income above £50,000. Determining return: 2024/25 SA return. Newly-mandated cohort estimated at around 130,000 landlords and self-employed taxpayers.
• Phase 2: mandate from 6 April 2027 for qualifying income above £30,000. Determining return: 2025/26 SA return. Newly-mandated cohort estimated at around 200,000.
• Phase 3: mandate from 6 April 2028 for qualifying income above £20,000. Determining return: 2026/27 SA return. Newly-mandated cohort estimated at 700,000 to 800,000.

Phase 3 is the bulk of the MTD ITSA programme. The earlier phases caught the largest landlords and the most professionalised businesses; phase 3 sweeps in the long tail, mid-tier landlords, accidental landlords, and small self-employed traders whose net profit is under £20,000 but whose gross crosses the threshold. That last group is where most of the surprises sit.

The 2026/27 determining return: when phase 3 status is set

HMRC tests your phase 3 eligibility against the qualifying-income figure on your 2026/27 SA return, filed in the ordinary course by 31 January 2028. The mandate notice follows in the months after that filing, ahead of the 6 April 2028 start.

Two things follow from this. If you expect to cross the threshold in 2026/27, treat that year's return as your trigger document. And if your 2026/27 income is borderline (close to £20,000), check the gross-rental figure carefully before you file. Over-state the gross by a few hundred pounds and you pull yourself into scope unnecessarily; under-state it and you may look out of scope on paper while being in scope on the real numbers, which is not a position you want to defend later.

Qualifying income: the gross-test definition

Qualifying income for the MTD ITSA threshold test is your gross self-employment income PLUS your gross property rental income, measured BEFORE any deductions. The two streams are added together, and your deductible costs are not taken off before the test is applied.

This gross test is the single feature of the threshold that catches people out. You might reasonably assume the test looks at net profit, where your taxable income sits comfortably below £20,000, only to find at the determining-return stage that the gross figure has pulled you in. The usual mismatches:

• High-mortgage BTL portfolios: gross rental £22,000, mortgage interest £14,000, agent fees and repairs £4,000, net profit £4,000. The gross test puts you in scope; your net profit says you should not be.
• Serviced-accommodation operators: gross rental £25,000, cleaning + utilities + platform fees £12,000, net profit £13,000. Gross test in scope; net profit only borderline for phase 3.
• Mixed rental and self-employment: £15,000 gross rental + £8,000 gross self-employment = £23,000 total qualifying income, above the £20,000 phase 3 threshold even though neither stream on its own would be.

If you are heading towards phase 3, model your gross rents forward from 2026/27. A property let at £1,200 a month produces £14,400 of gross rent a year, so two of them put you over the £20,000 threshold before you add a penny of self-employment income.

If you own property jointly, how does the test work?

Each owner tests against their share of the gross rent, not the property's total. For spouses the default split is 50/50 unless you make a Form 17 election. A Form 17 election (made under the Income Tax Act 2007 architecture, with TCGA 1992 consequences for the underlying ownership) can pull one spouse into scope before the other.

Default 50/50 split

Mr and Mrs Tasburgh own 2 jointly-held BTL properties with combined gross rental of £40,000 a year. A default 50/50 split gives each spouse £20,000 of qualifying income. Because the regulations bite on income "above £20,000", each spouse sits just BELOW the cliff on these facts and neither is mandated. The catch: a tiny rise in any future year (to £40,001 combined, £20,000.50 each) tips both of them into scope at once.

Form 17 election with uneven split

Mr and Mrs Pewsey have the same £40,000 combined gross rental but made a Form 17 election in 2022 to split it 75/25 in Mr Pewsey's favour. That changes everything:

• Mr Pewsey: 75% × £40,000 = £30,000 qualifying income. That meets the phase 2 threshold (above £30,000 from 6 April 2027), so he is in scope from the 2027/28 tax year onwards.
• Mrs Pewsey: 25% × £40,000 = £10,000 qualifying income. Below the £20,000 phase 3 threshold, so she is not in scope at any phase on current facts.

One property, two completely different timetables: Mr Pewsey must run full quarterly updates plus EoPS plus final declaration from 6 April 2027, while Mrs Pewsey stays in ordinary Self Assessment indefinitely. Worth knowing before you sign a Form 17 purely for income-tax reasons.

Worked example: bridge-population landlord at £22,000 gross

Mr Crowborough owns 2 BTL flats; gross rental income £22,000 per year; mortgage interest plus agent fees plus repairs leave £8,000 net profit. No other qualifying income.

Threshold testing:

• Phase 1 (above £50,000): £22,000 gross is below. NOT in scope from 2026/27.
• Phase 2 (above £30,000): £22,000 gross is below. NOT in scope from 2027/28.
• Phase 3 (above £20,000): £22,000 gross is above. IN SCOPE from 6 April 2028 (2028/29 tax year onwards).

His 2026/27 SA return (filed by 31 January 2028) is the determining return. Mr Crowborough needs to check his 2026/27 qualifying income against £20,000; if it is over, HMRC issues the mandate notice ahead of the 6 April 2028 start.

His runway:

• Q4 2026 to Q2 2027: choose MTD-recognised software from the gov.uk Find Software list.
• Q2 to Q3 2027: optionally opt in voluntarily for the 2027/28 tax year to pilot the workflow before the mandate bites.
• Q3 2027: if using an accountant, set up the Agent Services Account (ASA) authorisation. The legacy 64-8 paper authorisation does not work for MTD ITSA.
• 6 April 2028: mandated. Four quarterly updates per business stream plus EoPS plus final declaration.

Worked example: the gross-test trap with low net profit

Mrs Tunbridge owns 1 BTL property; gross rental £22,000 per year. Mortgage interest £14,000 plus agent fees £1,800 plus repairs £2,200 plus insurance £600 = total deductible costs £18,600. Net profit only £3,400.

Her qualifying income is the GROSS figure, £22,000, before deductions. That is above the £20,000 threshold, so Mrs Tunbridge is IN SCOPE from 6 April 2028 despite a net profit of only £3,400. Anyone in her position naturally assumes the test is on net profit, where £3,400 is nowhere near the cliff. It is not, and the gross test catches a real slice of the £20,000 to £50,000 bracket where the mortgage-interest restriction and other costs leave net profit very low.

The sting is in the workload. From 6 April 2028 she has to report gross rent and allowable deductions four times a year, the same quarterly burden as someone with £30,000 of net profit, on a far smaller tax bill. Proportionally, MTD ITSA costs you far more at the bottom of the phase 3 cohort than at the top.

Worked example: cross-stream aggregation puts a small landlord in scope

Mr Ashford owns 1 BTL flat; gross rental £15,000 per year. He also runs a small self-employed bookkeeping practice with gross self-employment income £8,000 per year.

Threshold testing: qualifying income = £8,000 self-employment + £15,000 rental = £23,000. Above £20,000 phase 3 threshold means Mr Ashford is IN SCOPE from 6 April 2028.

Counter-example: Mr Ashford's neighbour Mr Brackley has £18,000 gross rental and zero other qualifying income. Total £18,000. Below £20,000 means Mr Brackley is NOT in scope at any phase on current facts.

Two near-identical property positions, two different MTD outcomes. Side income you might think of as informal or hobbyist (online sales, freelance work, consultancy) counts towards qualifying income if it is reportable self-employment income. If you have a side line, add it to your gross rent at the gross level, not the net, and do not assume a small amount slips under the radar.

The MTD ITSA quarterly cycle

Once you are mandated, you have five obligations per tax year for each business stream:

• Quarterly update 1: covering 6 April to 5 July, due 7 August.
• Quarterly update 2: covering 6 July to 5 October, due 7 November.
• Quarterly update 3: covering 6 October to 5 January, due 7 February.
• Quarterly update 4: covering 6 January to 5 April, due 7 May.
• End of Period Statement and final declaration: due 31 January following the tax year end.

You can elect for calendar quarters instead (1 January to 31 March, 1 April to 30 June, 1 July to 30 September, 1 October to 31 December). The election is made annually and is handy if your records already run to calendar quarters.

If you have both rental and self-employment, each stream files its own four quarterly updates and its own EoPS, with the final declaration consolidated across all streams at year end. So one rental property plus one self-employment activity means 8 quarterly updates plus 2 EoPSs plus 1 final declaration, 11 obligations a year. That is a long way from the single annual return you file today.

The penalty regime: points-based late filing and accelerated late payment

Late filing: Schedule 55 FA 2009 points-based regime

Each missed quarterly update or EoPS earns 1 point under the Schedule 55 points framework as amended for MTD. Reaching the threshold (4 points for a quarterly filer; lower for less-frequent filers) triggers a financial penalty of £200. Subsequent missed submissions each attract a further £200 financial penalty until the points are reset by a continuous in-compliance period.

The points-based architecture is less punitive for a single isolated missed submission than the legacy Schedule 55 £100 immediate penalty; it is more punitive for sustained patterns of late filing because the £200 financial penalty bites repeatedly until the in-compliance period restores the points to zero.

Late payment: accelerated Schedule 56 schedule

The Schedule 56 late-payment schedule applies in an accelerated form to MTD ITSA filers from 6 April 2026 onwards (alongside the corresponding VAT MTD acceleration):

• From day 15: 3% of unpaid tax.
• From day 30: a further 3% of unpaid tax (cumulative 6%).
• From day 31: 10% per annum, charged daily, on the unpaid balance.

The legacy 5% / 5% / 5% Schedule 56 schedule still applies to non-MTD self-assessment filers. For MTD ITSA filers the acceleration is a genuine change to the cost of paying late, and it changes the maths if you have ever leaned on a deferred payment to manage cash flow. If you could shrug off the old 5% penalty at the 30-day mark, the 6% combined charge plus 10% per annum accruing daily is a different proposition.

Software readiness path

The MTD ITSA software market has matured significantly in the 2024 to 2026 window. HMRC maintains the recognised-software list at the gov.uk "Find software for Making Tax Digital for Income Tax" page; the list updates periodically as new products gain recognition. The recognised options fall into three categories:

• Full-stack accounting software: handles bookkeeping, MTD quarterly submissions, EoPS, and final declaration in one integrated workflow. Suits you if you want everything in one place.
• MTD-specific filing apps: focused on the MTD submission layer, designed to sit alongside a separate bookkeeping system or spreadsheet.
• Spreadsheet-plus-bridging: a spreadsheet (Excel, Google Sheets) as your underlying record, plus an HMRC-recognised bridging tool that submits the data to the MTD ITSA service. Fine, provided you keep the digital link intact throughout (no manual re-keying between the spreadsheet and the bridging tool).

If you are choosing software in 2026 or 2027, hold off and review options closer to the mandate (around Q2 2027) rather than locking in a product 18 months early. The recognised-software list will keep growing, pricing and integration will move, and the vendors will get noticeably slicker as the phase 1 and phase 2 cohorts shake the workflow out in real life.

Agent representation: the ASA flow

If you use an accountant, the authorisation route depends on the filing mode. Self Assessment accepts both the legacy 64-8 paper authorisation and the Agent Services Account (ASA). MTD ITSA accepts ASA only: a 64-8 does not authorise your agent for MTD ITSA quarterly or final-declaration submissions.

What that means in practice:

• You already have an accountant on a 64-8: they must move onto the ASA flow before the mandate starts. It is simple (the agent initiates the ASA authorisation and you confirm via Government Gateway), but it cannot wait until the first quarterly deadline.
• You are appointing a new accountant for MTD ITSA: they must use ASA from the outset. Any "I will sort the authorisation later" plan falls over at the first quarterly cycle.
• You change accountants mid-cycle: ASA authorisations do not transfer between agents. The outgoing agent's authorisation is revoked and the incoming one set up from scratch, so avoid switching mid-cycle if you can.

What if your income falls? The exit path

You can leave MTD ITSA if your qualifying income falls below the relevant threshold for three consecutive tax years. Exit is a positive notification to HMRC; do nothing and you stay in MTD ITSA even as your income drops.

That three-year buffer is deliberate. It stops people cycling in and out around the threshold, which would mean fresh software setup, fresh ASA authorisation and fresh quarterly-cycle re-orientation every time. It also means that if your income dips temporarily (a void period, a big refurbishment, a COVID-style market shock), you keep filing MTD quarterly right through the dip.

Re-entry is automatic once your income rises back above the threshold, and the same determining-return mechanic applies: the SA return for the year two before mandate sets the test. So if you exited at the end of 2031/32 and your 2033/34 SA return shows qualifying income back above the threshold, you would be re-mandated from 6 April 2035.

The LtdCo question: does incorporation take me out of MTD ITSA?

Yes. Limited companies are outside MTD ITSA. They file CT600 annually under the corporation tax regime, with the 12-month CT600 filing deadline under Schedule 18 FA 1998 and the 9-months-1-day CT payment deadline under TMA 1970 section 59D (or quarterly instalments for large companies above the £1.5 million augmented-profits threshold, subject to the associated-companies divisor).

For some, incorporation is an attractive way out of the MTD ITSA workload. For others the cost of incorporating dwarfs the saving:

• SDLT on transfer: properties transferred from individual to LtdCo attract SDLT at market value, with the 5% additional-property surcharge plus residential rates (the surcharge was raised from 3% to 5% on 31 October 2024 by FA(No.2) 2024). For a £400,000 BTL portfolio, SDLT on incorporation is around £30,000.
• CGT on transfer: the disposal from individual to LtdCo is a market-value disposal for CGT purposes, with chargeable gains crystallising. Incorporation relief under TCGA 1992 section 162 can defer the gain in narrow circumstances (where the property business meets the trade test, which is rare for passive BTL portfolios).
• Ongoing CT compliance: the CT600 cycle plus statutory accounts plus confirmation statement plus PAYE for director salary plus dividend documentation is a meaningful compliance overhead, although it is annual rather than quarterly.
• Dividend extraction: profits taken out of the LtdCo as dividends attract income tax at 10.75% / 35.75% / 39.35% (basic / higher / additional rates), on top of the 19% / 25% CT layer.

If you have phase 3 exposure, a long-term hold and rising profits, incorporation may net out positively over a 10-year horizon. If you hold a single BTL or plan to sell before long, the SDLT and CGT cost of incorporating usually swamps the MTD ITSA saving. Either way, get specialist advice on the full incorporation comparison before you let MTD ITSA become the reason you incorporate. The compliance burden is rarely the right tail to wag the dog.

The planning runway from today to 6 April 2028

If you are in scope for phase 3, you have roughly 18 to 24 months from now to the start. Here is a sensible order to work through:

1. Q4 2026 to Q1 2027: work out your expected 2026/27 qualifying income. If it is close to the £20,000 threshold, check the gross-rental figure carefully and decide whether you are genuinely above or below the cliff.
2. Q1 to Q3 2027: review software on the gov.uk Find Software list. Shortlist 2 to 3 products that fit your set-up (single BTL, multi-property portfolio, mixed rental and self-employment).
3. Q2 to Q3 2027: optionally opt in voluntarily from 6 April 2027 to pilot the workflow before mandate. The voluntary opt-in route is at gov.uk/guidance/sign-up-as-an-individual-for-making-tax-digital-for-income-tax.
4. Q3 to Q4 2027: if you use an accountant, set up the Agent Services Account authorisation and confirm their ASA capability and software compatibility.
5. Q4 2027 to Q1 2028: reconcile the joint-property arithmetic and Form 17 status with your co-owner. File any deferred Form 17 election ahead of the 2026/27 SA return.
6. Q1 to Q2 2028: file the 2026/27 SA return, confirm the qualifying-income figure, receive the HMRC mandate notice, and finalise your software setup.
7. 6 April 2028: mandate start. Your first quarterly update is due 7 August 2028, covering 6 April to 5 July 2028.

The phase 3 cohort is huge, and HMRC's processing of mandate notices from January to April 2028 will be busy. Leave your software, ASA authorisation or joint-property arithmetic to that window and your first cycle will be a scramble.

If your gross rents sit in the £20,000 to £50,000 bracket and you want a clear view of whether you are in scope, how the gross-test arithmetic lands on your own numbers, and what your runway should look like, this is exactly the kind of work we do: we take landlords through the MTD ITSA transition from the determining-return review to software selection, ASA setup, and support through that first quarterly cycle. Get the groundwork done early and the mandate becomes a non-event.