The question that lands in our inbox more than any other since HMRC started writing to landlords in late 2025 reads roughly like this: "I have £52,000 in rent but only £8,000 in profit after the mortgage and the agent. Am I in MTD?"

The answer is yes, and the page below is the long-form version of why. The Making Tax Digital for Income Tax Self Assessment regime tests gross turnover and gross rents, not net profit. Section 24 has already shaved your taxable margin to ribbons; the MTD threshold mechanic does not care. If the rent statements add up to more than £50,000 in the relevant reference year, you file digitally.

This page is the mechanic at the boundary, written for the people who actually need it: landlords whose gross is high but whose net is low. If you want the broader overview of who is exempt and which categories sit outside MTD entirely, the MTD threshold and exemptions pillar is the page for that.

The qualifying income test in one sentence

Qualifying income for MTD ITSA equals gross self-employment turnover plus gross UK and overseas property receipts, aggregated across all your trades and lets, measured for the reference year, before any expenses or reliefs come off. The statutory basis is Schedule A1 to the Finance (No. 2) Act 2017, as amended by subsequent Finance Acts to install the £50,000 / £30,000 / £20,000 phased thresholds.

The legislation uses the words "relevant amount of qualifying income". HMRC's operational guidance translates that as the figure you would put in the gross turnover and gross rents boxes of your self assessment return, summed without netting off costs. The test does not look at your tax bill, your net profit, or your finance-cost tax reducer. It looks at money in.

Three personas at the £50,000 boundary

Three composite portfolios drawn from anonymised case load. All three sit close enough to the threshold to be ambiguous on first reading. All three are caught.

Persona A: leveraged BTL landlord, £52,000 gross, £8,000 net

Three London flats, rented at £1,250, £1,400, and £1,700 per calendar month respectively. Gross annual rent £52,200. The portfolio carries £510,000 of buy-to-let mortgages at an average rate of 5.9%, so finance costs ran to £30,090. Letting agent at 10% retained £5,220. Repairs averaged £4,800 across three flats. Buildings and contents insurance £1,150. Council tax in voids £1,400. Accountancy £900. Net profit before the Section 24 tax reducer: £8,640.

For income tax the landlord is a higher-rate payer because of a £55,000 PAYE salary. Section 24 restricts the £30,090 of finance costs to a basic-rate 20% tax reducer, so the effective tax bill on the rental profit is roughly £3,500 to £4,000 after the reducer. The PAYE income is excluded from MTD qualifying income; the rent is included. £52,200 is above the £50,000 threshold for the 6 April 2026 mandate, and the landlord is in.

The point this persona illustrates: leveraged single-figure-net landlords are the largest population HMRC's letters target. The gross figure on the rent roll is what brings them in, not the modest tax bill.

Persona B: mixed self-employment plus rental, £56,000 combined

A freelance graphic designer with £32,000 of turnover in 2024/25, plus a single buy-to-let inherited from a parent generating £24,000 of gross rent. Aggregated qualifying income: £56,000. Above threshold, mandate effective from 6 April 2026.

This persona is the one most often surprised. The freelance side already files self assessment; the rental side is a small annex on SA105. Neither stream alone crosses £50,000, and the landlord's instinctive read is that they sit below the line. The aggregation rule catches them. The mandate covers both streams: the freelancer reports the design turnover quarterly through MTD software as self-employment, and reports the rent quarterly as property income, then files an annual end-of-period statement plus the final declaration.

Persona C: multi-property portfolio with full Section 24 bite

A higher-rate landlord with five flats acquired between 2014 and 2019, all on interest-only buy-to-let mortgages. Gross rent £82,000. Mortgage interest £41,000. Agent at 12% £9,840. Repairs over five years averaged £6,400. Insurance £2,100. Council tax in voids £2,500. Other deductibles £1,800. Net profit before the Section 24 reducer: £18,360.

After Section 24 restricts the £41,000 of finance costs to a basic-rate reducer, the effective tax on the rental profit at higher rate is around £15,000. The cash margin after tax and mortgage payments runs to single-digit thousands in a year with any vacancy.

The Section 24 reducer makes the tax position feel marginal, the cash position genuinely tight. None of that helps with MTD scope. £82,000 of gross rent is well above the £50,000 threshold and was above the £30,000 threshold that drops in from April 2027. The April 2026 mandate brings this landlord in; the second-stage drop does nothing because they were already in.

Where qualifying income lives on your self assessment form

To run the test yourself, pull your last filed return (the 2024/25 return is the reference year for the 6 April 2026 cohort) and read the following boxes.

SA105: UK Property pages

  • Box 20: rents and other income from property. This is your gross rent before any expense boxes.
  • Box 22: reverse premiums (where a landlord paid an inducement to take a lease, reverse premiums received by the property owner).
  • Box 23: deemed premium on grant of a short lease (50 years or less). ITTOIA 2005 treats part of the premium as deemed rent for the year of grant; that deemed amount counts toward qualifying income.

What you do not subtract: SA105 boxes 24 through 29 (rent paid, repairs, mortgage interest, other allowable property expenses, residential property finance costs not deductible). Those reduce taxable profit; they do not reduce qualifying income.

SA106: Foreign property pages

  • Box 14: total foreign property income, gross. Aggregates with SA105 box 20 for the MTD test.
  • Box 16: foreign lease premiums where applicable.

The fact that foreign property income may be relieved under a double tax agreement, or that it may be subject to overseas tax already, is irrelevant. The gross UK self-assessment-reported figure feeds the test.

SA103F and SA103S: Self-Employment pages

  • SA103F (full): box 15 (turnover) plus box 16 (any other business income not in turnover).
  • SA103S (short): box 9 (turnover) plus box 10 (any other business income).

Add the property gross figure to the self-employment gross figure. That total is your qualifying income for the reference year. If it exceeded £50,000 in 2024/25, the 6 April 2026 mandate caught you. If it exceeds £30,000 in 2025/26, April 2027 will. If it exceeds £20,000 in 2026/27, April 2028 will.

What counts as qualifying income

The inclusion list is short and specific. Anything from a property let or from a sole-trader business reported on the self-employment pages counts. That covers:

  • Standard residential and commercial rents.
  • Holiday let income (the furnished holiday let regime ended 6 April 2025; receipts now sit in ordinary property income and count in full).
  • Short-stay let income from platforms (Airbnb, Booking.com, SpareRoom, etc.).
  • Service charges retained by the landlord rather than passed through.
  • Premiums on short leases (the deemed-rent portion).
  • Reverse premiums received.
  • Insurance recoveries that replace lost rent (rent guarantee or loss-of-rent insurance proceeds).
  • Sole-trader turnover from any unincorporated business, regardless of sector.

HMRC's own eligibility checker, the "Check if you're eligible" gov.uk page, walks through these inclusions with worked examples; if a category is genuinely ambiguous (some service-charge structures sit on the border between rent and trust receipts), use the checker first and then take advice.

What does NOT count

The exclusion list is where most of the surprises lurk. None of the following enters the qualifying income figure:

  • Employment income reported via PAYE on SA102 (your salary is invisible to the test, even at £100,000).
  • Pensions and other annuity income on SA101.
  • Dividends, whether from your own company or from a quoted portfolio.
  • Bank and building society interest, gilts, and other savings income.
  • Partnership profit shares (deferred until MTD for partnerships commences; the deferral is HMRC's published position as at May 2026, with no firm start date).
  • Trust distributions reported by a beneficiary; the trust itself is outside MTD ITSA entirely.
  • Capital gains, even where the disposal generated significant cash.
  • Transition profits from basis-period reform spread under the FA 2022 transition rules.
  • One-off receipts that are not income (insurance settlements for capital losses, contractual damages outside the rent stream).

Two specific traps. First, dividends from your own property holding company do not count, even where the holding company exists to run the same rental business you used to run personally. That is one of the structural advantages of incorporating a portfolio: limited company rental income sits outside MTD ITSA entirely (companies file CT600s instead). Second, partnership profits do not count yet, but they will count once MTD for partnerships is switched on, and HMRC has signalled that the qualifying income aggregation rule will then bring sole-trader-plus-partner mixed cases into scope at lower combined thresholds.

The reference-year mechanic (CY-2)

HMRC tests qualifying income against the self assessment return for the year ending two years before the mandate start date. The schedule:

  • 6 April 2026 mandate: tested against the 2024/25 self assessment return (filing deadline 31 January 2026).
  • 6 April 2027 mandate: tested against the 2025/26 return (filing deadline 31 January 2027).
  • 6 April 2028 mandate: tested against the 2026/27 return (filing deadline 31 January 2028).

The two-year gap exists because HMRC needs your filed return to know your gross figures. The 2024/25 return for the April 2026 mandate was due by 31 January 2026; HMRC ran the qualifying income calculation across the filed population in spring 2026 and wrote to taxpayers it identified as above the threshold. The letters are not the legal trigger. The obligation belongs to the taxpayer the moment qualifying income for the reference year crosses the line, regardless of whether the letter arrives.

The Section 24 trap: why net-low landlords still get the letter

Section 24 ITA 2007 (introduced by FA 2015 s.24 and phased in from 2017/18 to 2020/21) restricts finance-cost relief for individual residential landlords to a basic-rate 20% tax reducer. Mortgage interest does not come off rental profit any more; it gives a tax credit at 20% against the overall income tax liability.

The structural effect: a landlord's taxable rental profit is the gross rent minus non-finance expenses (no mortgage interest deducted), and the tax bill on that taxable profit is then reduced by the 20% finance-cost reducer. For higher-rate taxpayers, the gap between taxable profit and economic profit widens.

This matters for MTD because the headline number on landlords' minds, the cash-margin-after-mortgage figure, is now structurally lower than it would have been a decade ago. Many landlords feel below threshold because their bank balance after the mortgage suggests a small business. The MTD test ignores both: it tests the rent invoiced to the tenant, before mortgage interest, before agent commission, before anything.

The practical consequence: the landlord cohort most affected by Section 24 is the same cohort most likely to be brought into MTD without expecting it. Higher-rate residential landlords with three to six properties on interest-only buy-to-let mortgages routinely sit in the £40,000-to-£90,000 gross-rent band with single-digit-thousand net margins. The April 2026 mandate caught the upper half of that range. The April 2027 drop to £30,000 catches almost all of it. The April 2028 drop to £20,000 catches the rest.

Joint owners and the share-of-gross sub-test

Joint property ownership splits the qualifying income figure between the owners according to beneficial ownership. The default position for spouses and civil partners is a 50/50 split absent a Form 17 election supported by a declaration of beneficial interest. For other joint owners (siblings, business partners holding property jointly outside a partnership structure, joint tenants and tenants in common generally), the split follows the actual beneficial ownership.

So a property generating £100,000 of gross rent held 50/50 between spouses tests at £50,000 each. Both spouses sit exactly on the boundary for the April 2026 mandate. A 75/25 Form 17 election would place the 75% spouse at £75,000 (clearly in scope) and the 25% spouse at £25,000 (below £50,000, but above £20,000, so caught from April 2028).

Form 17 election mechanics, the timing of beneficial-ownership declarations, and the interaction with the joint-tenancy versus tenants-in-common distinction are deep enough to need their own treatment. The MTD threshold and exemptions pillar covers the headline rule; sit with that page first if your portfolio is split across joint and sole holdings.

Edge cases at the boundary

Rent-a-room

The rent-a-room allowance (£7,500 per resident-landlord per tax year, halved if shared with another resident-landlord on the same property) sits outside qualifying income where the taxpayer elects rent-a-room treatment and stays within the allowance. If you opt out (because your costs exceed the allowance and a normal property computation is more favourable), the full gross lodger income enters the test. If you stay within the allowance but elect to be taxed on the excess, only the excess over £7,500 enters.

Foreign property and FHL transition

Foreign property income reported on SA106 box 14 counts in full, regardless of whether double tax relief reduces the UK tax bill to zero. The abolished FHL regime (gone from 6 April 2025) means that what used to be FHL receipts now sit in ordinary property income and aggregate with ordinary rents. A landlord who ran a holiday cottage as an FHL until April 2025 should expect the 2025/26 and later figures to be reported as ordinary property income, and to enter the qualifying income test accordingly.

Voids, arrears, and accruals

Property income on SA105 follows the accruals basis by default for landlords with gross rents above £150,000, and either accruals or cash basis at the taxpayer's election below £150,000. Voids are time periods with no tenant; they do not reduce gross rent in the way an expense would, because there is no receipt to start with. Arrears are accrued but uncollected rent: under the accruals basis the right-to-receive figure goes in qualifying income; under the cash basis only the actual receipts count. Choose the basis consciously, because it changes the qualifying income figure at the margin.

Lease premiums

A premium received for granting a lease of 50 years or less generates a deemed rental receipt under ITTOIA 2005 s.277. The deemed receipt formula is the premium times (50 minus N) / 50, where N is the number of complete years in the lease less one. That deemed receipt sits in SA105 box 23 and counts toward qualifying income. A £20,000 premium on a 21-year lease generates a deemed receipt of £20,000 times (50-20)/50 = £12,000, all of which feeds the MTD test. Premiums on leases longer than 50 years are entirely capital and do not enter the test.

What to do if the test puts you in scope

If you have run the test on your 2024/25 return and concluded that you are in MTD from 6 April 2026 (or 2027, or 2028, depending on which threshold catches you), the operational steps are these:

  1. Pick MTD-compatible software from the HMRC-recognised list at gov.uk's "Find software that's compatible" page. The list is updated regularly; spreadsheet-plus-bridging is acceptable provided the bridging product is on the list.
  2. Migrate your record-keeping to digital records covering each property and each trade you run. The records must capture the gross receipts and the allowable expenses on a transaction-by-transaction basis from the start of your first mandated tax year.
  3. Set up the quarterly cycle. Four updates per year, due 7 August, 7 November, 7 February, and 7 May for the standard UK tax-year quarters. Calendar-quarter elections are available from 6 April 2026 (filers can use 31 March / 30 June / 30 September / 31 December quarter-ends and file by the 7th of the following month).
  4. Plan for the end-of-period statement and final declaration, both due by 31 January following the tax year. The final declaration replaces the old SA100 self assessment return.
  5. Understand the new penalty regime. Late submissions accumulate points on a 4-point cycle for quarterly filers; the £200 penalty applies at the threshold and on each further late submission while at threshold. Late payment on the underlying tax follows the Spring Statement 2025 accelerated schedule: 3% from day 15, a further 3% from day 30, and 10% per annum from day 31. The previous 2%/2%/4% schedule on the 31/46/91 day-triggers continues to apply to VAT and to non-MTD income tax only.

The process side has its own dedicated page covering the practical switching workflow from annual SA to MTD quarterly: how to switch from self assessment to MTD for property income. The wider mandate overview, including all the exemption categories outside the gross test, sits at the MTD property income complete guide.

The bottom line

MTD ITSA tests gross. Section 24 will not get you out, an expensive mortgage will not get you out, a heavy agent's cut will not get you out, and a long string of repairs will not get you out. The rent on the rent statements is the number that counts, and it is the number HMRC uses to decide which mandate year reaches you.

If your gross is comfortably above £50,000, you are already in. If your gross sits between £30,000 and £50,000, the April 2027 drop will catch you. If your gross sits between £20,000 and £30,000, the April 2028 drop reaches you. The qualifying income mechanic is the same in each case; only the threshold moves. Know your gross figure, know which return decides your mandate year, and act before the first quarterly cycle begins, not after the first missed deadline.