MTD ITSA Join Date + Deadline Checker
Tells you whether you have to use Making Tax Digital for Income Tax, the exact tax year you join, and every quarterly + Final Declaration deadline once you're in. Live-recompute — update any field and the answer moves.
Records ready before quarter one
PocketReceipt logs every receipt and mileage entry against the right MTD quarter from day one, so the cumulative figures are there when 7 August comes around. Free on iOS and Android.
How MTD ITSA mandation actually works
Making Tax Digital for Income Tax rolls in over three phases between April 2026 and April 2028. Each phase tests your qualifying income for one specific tax year. If you're over the threshold for that year, you're in. If you're under, you wait for the next phase to test you against a different year and a lower threshold.
The three phases — locked dates
| Tax year tested | Threshold | Mandated from | First quarterly deadline | First Final Declaration |
|---|---|---|---|---|
| 2024/25 | £50,000 | 6 April 2026 | 7 August 2026 | 31 January 2028 |
| 2025/26 | £30,000 | 6 April 2027 | 7 August 2027 | 31 January 2029 |
| 2026/27 | £20,000 | 6 April 2028 | 7 August 2028 | 31 January 2030 |
HMRC pulls your qualifying income from the Self Assessment return you've already filed for the tested year. You don't choose which year is tested — the year is fixed by the phase.
What counts as qualifying income
HMRC's official definition:
- Gross income, not net. Use turnover, not profit. Don't deduct expenses, the trading allowance, or the property allowance when checking the threshold.
- All your self-employment income (every trade or profession combined, not per-business).
- All your property income — UK and foreign for UK residents; UK only for non-residents.
- Does not include employment income, pensions, dividends, savings interest, or capital gains.
If you have both self-employment and property income, add them together. The £50,000 threshold isn't "£50,000 from one source" — it's the combined total.
What happens if you cross the threshold mid-year
The test is against the tax year HMRC names in each phase. If your 2024/25 income was £45,000 (under threshold) but your 2025/26 income jumps to £55,000, you don't get mandated in April 2026 — you get caught by the £30,000 test for 2025/26 and mandated from 6 April 2027. Each phase tests its specific year, not "any recent year".
What happens if you're below all three thresholds
You're not mandated. You can carry on filing the standard once-a-year Self Assessment return by 31 January. You can also voluntarily sign up for MTD ITSA early if you want the quarterly rhythm. HMRC may extend the regime to lower thresholds in future Budgets — when that happens we'll update the tool.
Once you're in: the quarterly deadlines
Quarterly updates are cumulative — each one reports the year-to-date totals, not just that quarter's figures. The four standard quarters end on 5 July, 5 October, 5 January and 5 April. The submission deadline is one calendar month and two days after the period ends — so always the 7th of August / November / February / May. Final Declaration (the new replacement for the traditional Self Assessment return) is due 31 January after the tax year ends.
The penalties if you miss them
2026/27 has a soft-landing year for quarterly updates only — they don't earn penalty points. Final Declaration and late tax payments are penalised in full from day one. From 2027/28 onwards every missed submission earns a point, with a £200 fine at 4 points. See our MTD Penalty + Interest Calculator for the exact figures and the post-April 2025 late-payment regime.
Sources: HMRC — Find out if and when you need to use MTD for Income Tax; HMRC — Work out your qualifying income; Reduction of the mandation threshold from £30,000 to £20,000 from April 2028. Related tools: MTD Payment Forecaster for projecting tax owed, MTD Penalty Calculator for the late-filing and late-payment math, and our MTD ITSA quarterly checklist.