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What is Income Tax Self Assessment (ITSA)?
Last verified 31 October 2026
Income Tax Self Assessment, or ITSA, is the system HMRC uses to collect Income Tax from people whose tax is not fully deducted at source, such as landlords. MTD for Income Tax, sometimes written MTD ITSA, changes how you keep records and report within that system.
Why it matters to landlords
HMRC describes Self Assessment as the way people and businesses with other income report it in a return, because tax on wages and pensions is usually deducted automatically. Making Tax Digital does not replace it. Exempt taxpayers, for example, must continue to report income and gains in a Self Assessment tax return as normal, and you must still submit a return for the tax year before you start using MTD.
What changes for MTD users is the route. You create digital records, send quarterly updates through compatible software, and complete and submit the tax return through software too. Income Tax categories stay the same as Self Assessment. Payment deadlines are unchanged: for 2026 to 2027 the return is submitted and the tax paid by 31 January 2028, according to HMRC's first-year timetable. Other income such as pensions, savings and dividends still goes on the same return.
Example
Abby lets two houses and has an employer pension. For 2026 to 2027 she sends four quarterly updates for the rent, then in January 2028 completes her return in her MTD software, adding the pension, and pays her bill by 31 January 2028.
What Is Making Tax Digital? The 2026 Income Tax Guide →
Related terms
- Self Assessment
- MTD for Income Tax (MTD ITSA)
- Final declaration
- SA100 tax return
- Self Assessment deadlines