Most of the questions we get about Making Tax Digital for Income Tax are not really about the software. They are about one thing: am I in it or not? And the answer catches people out, because the test is not what you would assume.
It is tested on a return you have already filed
The threshold is not applied to what you expect to earn this year. It is applied to your qualifying income on your previous tax return. So whether you were mandated from April 2026 was decided by the return you filed by 31 January 2026, a figure fixed before anyone asked you about it.
That matters because it removes the option of managing your way out of it. By the time you are wondering whether you are affected, the number that decides it has already been submitted.
It is gross income, not profit
This is the one that surprises people most. Qualifying income means turnover before expenses, not the profit you actually live on.
If you invoice £80,000 and your costs are £30,000, your qualifying income is £80,000. You are over the £50,000 threshold, even though your profit is comfortably under it. A landlord with £55,000 of rent and a large mortgage might be barely breaking even and still be firmly inside the regime.
Self-employment and property are added together
The test looks at your combined qualifying income. A consultant billing £35,000 who also has £20,000 of rental income is at £55,000 and is caught, even though neither stream on its own would have been.
Two modest income sources are a common shape among our clients, and it is exactly the shape most likely to be missed.
The dates, and what actually changes
The threshold steps down twice more: £30,000 from April 2027, and £20,000 from April 2028, which is the final announced phase. Each step brings in a much larger group than the one before.
Quarterly updates fall due on 7 August, 7 November, 7 February and 7 May, covering the quarters to 5 July, 5 October, 5 January and 5 April. They are summaries rather than full returns, filed from MTD-compatible software rather than typed into a form. After the year end, a final declaration pulls everything together and replaces the return you are used to.
The practical change is smaller than the noise around it suggests, but it is real: the bookkeeping can no longer wait. You cannot summarise a quarter you have not recorded. A shoebox and a spreadsheet in January stops being an option.
A few things that are not caught
A limited company's turnover does not count towards your personal threshold. What counts is your own self-employment and property income; the company has its own obligations, including MTD for VAT if it is registered.
Those completing the residence pages of their return had a one-year deferral to April 2027. Partnerships are confirmed as coming but with no date announced, though individual partners with other qualifying income are still in scope on their own account.
And if you are below the threshold, nothing is required of you yet. You can join voluntarily if you would rather move on your own timetable than be moved on someone else's.
What we would do
If you are unsure, the check takes minutes: we look at the return you have already filed and tell you which cohort you are in. If you are already on Xero and reconciled monthly, the honest answer is usually that almost nothing changes for you. If you are not, the work is in getting the records current, and that is easier done now than in the quarter it becomes compulsory.
Common questions
Does MTD for Income Tax apply to my limited company?
No. The threshold looks at your personal self-employment and property income only. Company turnover does not count towards it. The company has its own obligations, including MTD for VAT if it is registered, but those are separate.
Is the threshold based on profit or turnover?
Turnover, before expenses. This is the single most misunderstood part of the rules. You can invoice £60,000, spend £25,000 running the business, and be inside the regime on a profit of £35,000.
What happens if my income drops below the threshold?
You do not fall out of the regime immediately. Once you are mandated you generally stay in, and coming back out requires your qualifying income to be below the exit level across three consecutive years. Plan on the basis that entry is easier than exit.
Do I have to use Xero for MTD for Income Tax?
No. Any MTD-compatible software will do, and HMRC publishes a list. What you cannot do is keep records on paper or in a spreadsheet with no bridging software and file directly to HMRC through a web form. That route is closing.
What are the penalties for missing a quarterly update?
Late submissions attract points under HMRC's points-based penalty system, with a financial penalty once you reach the threshold for your filing frequency. Interest also runs on tax paid late, separately from the penalty.
I am already on Xero and reconcile monthly. What changes for me?
Very little. The quarterly update is generated from records you are already keeping. The change bites hardest on people who currently do a year's bookkeeping in one sitting before the January deadline.
