Income Tax Self Assessment (ITSA)
Quarterly updates, the in-year calculation, year-end adjustments and the Final Declaration under Making Tax Digital for Income Tax.
Income Tax Self Assessment (ITSA)
Making Tax Digital for Income Tax replaces the annual Self Assessment return for sole traders and landlords with quarterly updates sent from software and a Final Declaration at the end of the year. dynamik.app prepares both from the records you already keep.
dynamik.app is built on HMRC's Making Tax Digital APIs and prepares your returns for filing. Our application for HMRC recognition is in progress; filing to HMRC switches on when it is approved.
Who Needs MTD for Income Tax?
HMRC phase it in by gross income from self-employment and property combined:
| From | Gross income above |
|---|---|
| April 2026 | £50,000 |
| April 2027 | £30,000 |
| April 2028 | £20,000 |
Below the threshold you can still join voluntarily.
Connecting to HMRC
- Go to Accounts > Tax & Compliance > HMRC Settings
- Click Connect to HMRC
- Sign in with your Government Gateway user ID and password
- Authorise dynamik.app to view and submit on your behalf
One connection covers VAT and Income Tax. It lasts 18 months; the page tells you when it needs renewing.
Your Businesses
Each self-employment and each property business HMRC hold for you is listed on the Obligations page with its own set of periods. If the page says No Business Records Found, the business has not been signed up for MTD for Income Tax with HMRC yet — that is done with HMRC, not in dynamik.app.
Quarterly Updates
The standard quarters run from 6 April:
| Quarter | Period | Deadline |
|---|---|---|
| Q1 | 6 April – 5 July | 7 August |
| Q2 | 6 July – 5 October | 7 November |
| Q3 | 6 October – 5 January | 7 February |
| Q4 | 6 January – 5 April | 7 May |
To send one:
- Open HMRC Settings > Income Tax > Obligations
- Pick the open period and click Submit update
- Review the income and expense totals dynamik.app has built from your invoices, bills and expenses for the period
- Click Submit to HMRC — the receipt is kept against the period
In-Year Calculation
At any point in the year, Calculation asks HMRC for an estimate of the Income Tax and National Insurance due so far, based on the updates sent. It is an estimate, not a bill.
Year End
After the fourth quarter, Year-end is where the annual figures are finished before the declaration. Open it from Obligations > Year End, pick the business and the tax year, and work through the tabs. What is on each tab depends on the business: a trade and a UK property business file different allowances and different kinds of loss.
| Tab | What you do there |
|---|---|
| Annual Submission | Capital allowances and adjustments for the year, then Save Annual Submission. For a UK property business this includes the Property Income Allowance (up to £1,000, instead of the other allowances), the non-resident landlord declaration and Rent a Room relief. Withdraw Annual Submission removes everything saved for that business and year. |
| Accounting | Cash basis or accruals, periods of account, and the late accounting date rule. |
| Adjustable Summary | Generate Summary asks HMRC for the business source adjustable summary of the figures you sent. View shows its totals before and after adjustments; Adjust sends accounting adjustments. |
| Losses | For 2025-26 and earlier: brought forward losses (for a trade, ordinary or Class 4) and loss claims. Open a loss to change its amount or delete it, or a claim to change its type. With carry-sideways claims, number them to set the order HMRC use them in and Save Order. For 2026-27 onwards HMRC keep one record per business per year, Losses and Claims: carry back (against last year's general income, early years losses, terminal losses), carry sideways, carry forward, which to apply first when there is both a carry back and a carry sideways, and the losses brought forward into the year. Save Losses and Claims replaces what HMRC hold for the year. |
| Tax Liability | Adjustments to the year's tax bill that are not income: the decrease from carrying this year's losses back to an earlier year (Income Tax, Class 4 National Insurance, Capital Gains Tax). One set per person per tax year, sent with Save Adjustments after the year has ended. |
Every figure goes to HMRC as you save it, and the page shows HMRC's own reason if they refuse one.
Some year-end items are not built yet: structures and buildings allowances, and foreign property (refused, as everywhere in the app). HMRC's losses service for 2026-27 onwards is still in testing at HMRC. Tax liability adjustments start at 2026-27. For anything not here, use software from HMRC's compatible software list.
Final Declaration
The Final Declaration replaces the Self Assessment tax return. It confirms your total taxable income for the year from all sources and is due by 31 January after the tax year. Once one has been submitted for a tax year, the page says so and will not let a second one go.
There is no longer an End of Period Statement. HMRC removed it; the year-end adjustments and the Final Declaration cover what it used to do.