Personal Income Tax Return (Form IT1)
Annual Isle of Man income tax self-assessment return for resident individuals with income from employment, self-employment, property, investments or other sources. Filed with the Assessor of Income Tax. The return covers the tax year 6 April to 5 April, with a deadline of 6 October (6 months after year-end).
Who this applies to
- Isle of Man residents with self-employment income
- Company directors with income not fully taxed under ITIP
- Individuals with Isle of Man rental or property income
- Individuals with investment or overseas income
- Anyone issued with a notice to file a return by the Assessor
What to file
Form IT1 (Individual Income Tax Return) detailing all sources of income including employment (ITIP summaries), self-employment (accounts or computation), rental income, and investment income. Claim personal allowances, reliefs and losses.
How to file
Online via myGov.im (preferred) or by paper return to the Assessor of Income Tax. Online filing is encouraged and gives instant confirmation of receipt.
Payment due
Any balance of tax due after ITIP deductions is payable by the same 6 October deadline. If a payment on account was required (for significant non-ITIP income), an earlier instalment may have been due.
Penalties for missing this deadline
Fixed penalty of £250 for filing after the 6 October deadline. Additional penalties for tax-related inaccuracies and late payment interest. The Assessor can make a determination if no return is filed and charge tax based on that determination.
Filing checklist
- Gather ITIP P60 or equivalent for employed income
- Prepare self-employment accounts and profit computation
- List all rental income and allowable expenses
- Include dividends and investment income
- Claim all eligible personal allowances (£14,500 for 2025/26)
- Calculate and pay any balance of tax due by 6 October
- Keep evidence of all figures for at least 5 years
Common mistakes to avoid
- Missing the 6 October deadline — many individuals confuse it with the UK's 31 January SA deadline, which does not apply in the Isle of Man
- Forgetting to include dividend income from Isle of Man or overseas companies
- Not claiming all eligible personal allowances and reliefs
- Directors failing to include all benefits in kind received from their company
Never miss a Isle of Man deadline
AccountsOS tracks every Income Tax Division (Treasury) and Isle of Man Companies Registry deadline and reminds you weeks ahead.
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