The M-Form: Filing for Your Migration Year

The Dutch tax year you move in or out is filed on a different form — the M-form. It exists because your tax status changes mid-year: non-resident before arrival, resident after. The Belastingdienst wants to know your worldwide income for the resident portion of the year and your Dutch-source income for the non-resident portion. The form is materially more complex than the standard P-form, and it is the single most common reason for refund delays in the first year of Dutch tax life. This page covers what to do, when, and where most expats trip up.

At a glance — key facts

  • The M-form is for the year you migrated in to or out of the Netherlands.
  • File by 1 July of the following year (vs 1 May for the P-form).
  • Splits the year into a resident and a non-resident period.
  • Foreign income before arrival is reported but only for treaty-rate purposes.
  • After your full first calendar year of residency, you switch back to the P-form.
  • Most expats use a tax advisor for the M-form year; the form is significantly more complex.

Who files an M-form and when

You file an M-form if:

– You became a Dutch tax resident during the tax year (typically when you registered at the municipality after moving), or
– You stopped being a Dutch tax resident during the year (you moved out and de-registered).

You do not file an M-form if:

– You moved in or out before January of the previous tax year — that year was your M-form year; this year is a P-form year.
– You were a non-resident with Dutch income (different form: the C-form).

The M-form filing deadline is 1 July of the following year. Extensions to 1 May of the year after are usually granted on request. Penalties for missing the deadline are limited but the bigger cost is delayed refunds — most M-form filers are owed a refund because of partial-year deductions and unused tax credits.

What is different from the P-form

The M-form splits your year into two periods:

1. The resident period. Worldwide income for the months you were a Dutch tax resident. Standard Box 1, 2 and 3 rules apply.
2. The non-resident period. Dutch-source income only for the months you were not a Dutch tax resident. Income earned abroad in this period is reported for treaty-rate-determination purposes but is generally not taxed in the Netherlands.

The form asks for:

– Date of arrival or departure.
– Income from all sources for both periods.
– Foreign tax paid in the non-resident period (relevant for treaty calculations).
– Box 3 wealth on the date of arrival or departure (the snapshot taken for the resident period).
– 30% ruling beschikking, if you applied for it.

The mortgage interest deduction, eigenwoningforfait and other Box 1 items are pro-rated for the resident period only.

The five most common M-form mistakes

After 30+ years of filing these for expats arriving in Brainport and Arnhem-Nijmegen, the same mistakes show up:

– Filing a P-form by accident. The Belastingdienst auto-issues a P-form invitation for everyone. If you migrated, you have to request the M-form yourself or your advisor does.
– Reporting full-year income. Salary earned abroad before moving belongs in the non-resident period for treaty purposes, not in Dutch Box 1. Many filers report all 12 months as Dutch — the result is over-taxation that takes months to correct.
– Box 3 snapshot at the wrong date. Box 3 wealth is measured on 1 January of the year for full-year residents, but for migration years it is measured on the date of arrival. Use the arrival-date balance, not 1 January.
– 30% ruling not yet granted. If your beschikking arrives after you file, you can amend the M-form to include the ruling retroactively. Many filers wait and miss meaningful refunds.
– Partner income mismatch. If your partner arrived on a different date, each files their own M-form covering their own resident period. Joint allocation of mortgage interest etc. only applies during the months you were both resident.


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Frequently asked questions

The year you migrated is an M-form year. The next full calendar year is a P-form year, assuming you were a resident for all 12 months of that year.

Yes. Even a one-month resident period triggers the M-form. The refund is often small but the filing is still required.

You are still a Dutch tax resident on the date you registered. The family situation may matter for treaty residency questions if your country of origin also claims you as resident — talk to an advisor before filing.

Yes, since 2023 the M-form is available in the Belastingdienst Mijn Belastingdienst portal. Earlier years required a paper form. Most expats still use an advisor because of the complexity.

Yes, for the months you were a resident and the ruling was active. The pro-rated benefit goes into the Box 1 calculation for the resident period.


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Reviewed by Joan Ottenheim, CFP & FFP — last reviewed 2026-06-03.