MTD ITSA is mandatory from April 2026. SubmitFox handles your quarterly updates with a simple CSV upload — no accountant, no complexity.
Making Tax Digital for Income Tax Self Assessment requires self-employed people and landlords to submit a summary of income and expenses every quarter — using compatible software only.
Think of it as four small check-ins per year instead of one big annual return. Each quarter you submit a summary. At year end you make a Final Declaration — replacing the traditional SA100.
Get started for free →Each quarter you upload a summary of income and expenses. HMRC receive a running picture of your finances — no big year-end surprise.
End of year: Final Declaration — replaces the traditional Self Assessment SA100. You confirm all figures, add any other income (employment, dividends, savings), and pay any tax due. Deadline: 31 January — same as always.
Whether you use a spreadsheet or accounting software, SubmitFox bridges your records directly to HMRC every quarter.
Get our pre-formatted CSV template for your income type. Already use a spreadsheet? We recognise 50+ common column formats automatically.
Free download — no account requiredEnter your year-to-date income and expenses. SubmitFox validates your figures, flags issues, and shows an instant tax estimate before you submit.
Real-time HMRC validationOne click submits your quarterly update via HMRC's MTD API. You receive a confirmation reference immediately. Done until next quarter.
Direct HMRC MTD API connectionNo subscription. No monthly fee. No upfront cost. Complete your return for free and pay only when you're ready to submit to HMRC.
No credit card required to start
HMRC will issue penalty points for late or missing quarterly updates, similar to the existing points-based system for VAT. Once you accumulate enough points, financial penalties apply. From April 2026 this system replaces the old fixed-rate penalties for income tax.
The traditional Self Assessment SA100 is replaced by the MTD Final Declaration — submitted at the end of the tax year. The deadline remains 31 January. The process is similar but done through MTD-compatible software like SubmitFox instead of the HMRC portal.
Yes. SubmitFox accepts CSV or Excel uploads and automatically recognises 50+ common column formats. If your spreadsheet has date, income, and expense columns, SubmitFox will map them correctly. You can also download our template to use from the start.
You'll need to submit quarterly updates for each income source separately. SubmitFox supports both self-employment and property income in the same account. Each source is submitted as a separate quarterly update to HMRC.
Yes. SubmitFox is HMRC-recognised software for MTD and submits directly through HMRC's official MTD API — the same API used by all compatible MTD software.
The £50,000 threshold applies to your qualifying income from self-employment and property combined for the previous tax year. If you're unsure, start free — SubmitFox will show you whether MTD ITSA applies to you. See our guides for more detail.
Bridging software connects your existing records (spreadsheets, accounting software exports) to HMRC's MTD API. SubmitFox is bridging software — you keep using whatever you already use to track income and expenses, and SubmitFox handles the HMRC connection.
Get set up now so your first quarterly update takes minutes, not hours. Free until you submit.
Start for free →