Making Tax Digital for Income Tax started on 6 April 2026 for anyone with qualifying income over £50,000, tested on their 2024/25 return. Qualifying income is gross income from self-employment and property before any allowances or expenses — so it is a locum's turnover that decides the question, and that is where most people get it wrong.
Article · 6 August 2026
Making Tax Digital for Income Tax is live. It began on 6 April 2026 for individuals whose qualifying income exceeded £50,000, measured on the 2024/25 tax return, and roughly 780,000 individuals are in that first tranche.
The single most common mistake a self-employed locum makes about it is assuming the test looks at profit. It does not. Qualifying income is gross income from self-employment and property, before any allowances or expenses. For a locum vet that means the total invoiced, not what was left after mileage, accommodation, indemnity cover, registration fees and an accountant.
Three different numbers, three different test years and three different start dates. Keeping them apart is most of the work.
| Qualifying income over | Tested on the tax year | Mandatory from |
|---|---|---|
| £50,000 | 2024/25 | 6 April 2026 |
| £30,000 | 2025/26 | 6 April 2027 |
| £20,000 | 2026/27 | 6 April 2028 |
The test looks backwards. HMRC checks the Self Assessment return for the relevant year, and it is the previous year's return that determines the obligation. Someone joining on 6 April 2026 was caught by what their 2024/25 return said — a return filed by 31 January 2026 and now unalterable.
Which makes the last row the interesting one. The £20,000 threshold is tested on 2026/27, the tax year running right now. A locum whose gross fees will land anywhere near £20,000 this year is deciding today, by how they keep their records, how comfortable April 2028 is going to be.
Two illustrative locums, both convinced they are outside the regime.
The pattern is consistent. Anyone whose costs are high relative to fees — heavy mileage, overnight stays, equipment — has the widest gap between the number they think about and the number HMRC tests. A locum working across a wide geography is precisely that person.
This is the second thing that surprises people. A quarterly update is not a report on the three months just gone. Each period runs from 6 April, so every update restates the year to date.
| Update period | Deadline |
|---|---|
| 6 April to 5 July | 7 August |
| 6 April to 5 October | 7 November |
| 6 April to 5 January | 7 February |
| 6 April to 5 April | 7 May |
Updates can be sent any time from the end of the period to the deadline, and up to ten days early where no further transactions are expected.
The cumulative design has a genuine upside worth understanding, because it changes how much a mistake costs. If a June invoice was entered wrongly and you spot it in September, you do not amend the first update — you correct the record, and the second update, which covers 6 April to 5 October, carries the corrected figure automatically. The obligation is to keep the running record right rather than to get each quarter perfect on the day.
The downside is rhythm. Four submissions a year plus a final declaration is a different working pattern from one annual return, and it does not tolerate a shoebox of receipts opened in January. The records have to exist as you go.
Stated as a fact about scope, because it is one: Making Tax Digital for Income Tax applies to sole traders and landlords. Companies are not in it. A locum working through their own limited company has no MTD for Income Tax obligation in respect of the company's income, however large the turnover.
That is not an argument for incorporating, and it should not be treated as one. A company brings corporation tax, the dividend rates that rose on 6 April 2026, payroll and RTI, statutory accounts and a confirmation statement, the associated-companies question if there is more than one company, and the IR35 or off-payroll analysis on every engagement. Trading through a company to avoid four quarterly updates would be a large decision taken for a small reason. The scope point matters for a different purpose: it tells a locum who already operates through a company that the emails about April 2026 were not about them.
Note also what remains true either way. VAT is a separate regime with a separate threshold — a registration requirement at £90,000 of taxable turnover in the previous 12 months, or where that is expected to be exceeded within 30 days — and MTD for VAT already applies to every VAT-registered business.
They are real but narrow, and applied for rather than assumed. HMRC operates an exemption process covering circumstances including digital exclusion. A locum who genuinely cannot use digital tools, or for whom it is not reasonably practicable, has a route — but it is an application with a decision at the end of it, not a self-assessment of inconvenience.
Take your gross fees for the 2026/27 tax year to date, before deducting a single expense, and add any rental income. That figure, annualised, tested against £20,000, tells you whether 6 April 2028 applies to you. If it does, the choice is between building the habit now while nothing depends on it, or building it in the first quarter that does. There is no version where the record-keeping is optional.
The mechanics, software and quarter-by-quarter workflow are in the MTD guide for locum vets, and what is actually deductible against locum work is in the locum tax guide. The service side is locum vet accounts, with the take-home arithmetic in the locum take-home calculator. Whether an engagement is inside or outside the off-payroll rules is a separate question, covered in the IR35 guide. This is general information rather than advice on your own position.
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It depends on your gross income, not your profit. Making Tax Digital for Income Tax started on 6 April 2026 for individuals whose qualifying income exceeded £50,000 on their 2024/25 return, extends to those over £30,000 tested on 2025/26 from 6 April 2027, and to those over £20,000 tested on 2026/27 from 6 April 2028. Qualifying income is gross income from self-employment and property before allowances or expenses, and the two are added together. A locum invoicing £62,000 with £14,000 of costs has qualifying income of £62,000, not £48,000, and has been in scope since 6 April 2026.
Because that is how HMRC has defined qualifying income: gross income from self-employment and property, tested before any allowances or expenses are deducted. It is a deliberately blunt measure, and it has the effect of pulling in people whose profits are well below the threshold. Locum vets are unusually exposed to that gap, because mileage across a wide geography, overnight accommodation, professional indemnity cover, registration fees and equipment can put a substantial distance between fees invoiced and profit taxed. The number to test is always the top line of the relevant year's return, plus any rents.
There are four, with deadlines of 7 August, 7 November, 7 February and 7 May. The important feature is that the periods are cumulative rather than discrete: each one runs from 6 April, so the second update covers 6 April to 5 October and restates the first period as well as the months since. Updates can be sent any time between the end of a period and the deadline, and up to ten days early where no further transactions are expected. The practical effect is that a mistake spotted later is corrected in the running record and flows through the next update automatically.
No. Making Tax Digital for Income Tax applies to sole traders and landlords registered for Self Assessment. Companies are outside its scope entirely, so a locum operating through their own limited company has no quarterly update obligation in respect of the company's income, whatever its turnover. That is a fact about scope rather than a reason to incorporate: a company brings corporation tax, the dividend rates that rose on 6 April 2026, payroll, statutory accounts and an off-payroll analysis on every engagement. MTD for VAT is separate and already applies to every VAT-registered business.
There is an exemption process and it covers circumstances including digital exclusion, where it is not reasonably practicable for someone to use digital tools to keep records or make submissions. It is an application to HMRC with a decision at the end of it, not something a taxpayer decides for themselves, and inconvenience or dislike of software is not the test. For most locum vets the more useful question is the practical one: whether the records are already being kept in a form that can produce four cumulative updates a year without a reconstruction exercise every quarter.
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