M return 2025: guide for expats moving in or out

What is the M return?

The M return is the Dutch income tax return for the year in which you move to the Netherlands or leave it. The tax year is then split into a Dutch period and a foreign period.

When do you need it?

• You moved to the Netherlands in 2025.
• You left the Netherlands in 2025.
• You spent part of 2025 living in the Netherlands and part outside it.

When do you file the 2025 M return?

According to the Belastingdienst, the online 2025 M return can be filed from 1 May to 1 July 2026. In Mijn Belastingdienst you choose the return for taxpayers who lived outside the Netherlands for part of the year.

If you cannot or do not want to file online, you can request a paper M form. For entrepreneurs, paper filing may also require separate M financial statements.

Extension

If you request an extension for your 2025 M return before 1 July 2026, the deadline usually moves to 1 November 2026. Up to 1 May this can be done in Mijn Belastingdienst; up to 1 July it can also be done by phone or in writing.

What information do you need?

• The date you registered or deregistered
• Income information from the Netherlands and the other country
• Information about bank accounts and assets on 1 January
• WOZ and mortgage information if you have a home
• Any information about the 30% ruling, pension, and foreign income

Common mistakes

• Using the regular return even though you lived outside the Netherlands for part of the year
• Allocating foreign-period income incorrectly
• Forgetting that box 3 and deductions can differ by period
• Starting too late even though the M return only opens from 1 May

The M return is still one of the most complex Dutch tax returns. But based on the current Belastingdienst information, for 2025 you are no longer limited to a paper-only process.