TL;DR
The M-form is a special Dutch tax return for the year you moved to or from the Netherlands. It covers a partial tax year and is more complex than the regular C-form. Most expats are entitled to a refund. The form is paper-only and cannot be filed online. Deadline: July 1 of the following year. Cost for professional filing: €250–500.
What is the M-form?
The M-form (migratieformulier) is the Dutch tax return for the calendar year in which you immigrated to or emigrated from the Netherlands. The “M” stands for migratie (migration).
If you arrived in the Netherlands partway through the year, you were a non-resident for part of the year and a resident for the rest. The M-form captures both periods and applies different tax rules to each. This is what makes it more complex than the regular annual tax return (the C-form).
M-form vs. C-form vs. P-form
- M-form: Migration year — the year you moved to/from the Netherlands
- C-form: Regular annual tax return for full-year residents
- P-form: Also the regular annual return (used interchangeably with C-form)
Who needs to file an M-form?
You should file an M-form if:
- You moved to the Netherlands partway through a calendar year
- You left the Netherlands partway through a calendar year
- You earned Dutch income during the year of your migration
Even if filing is not strictly mandatory, it is almost always beneficial. Most expats who file an M-form receive a refund because:
- Tax credits are pro-rated: The arbeidskorting (employment tax credit) and algemene heffingskorting (general tax credit) are based on full-year income, which is lower when you only worked part of the year.
- 30% ruling retroactive application: If your 30% ruling was approved after you started working, the M-form can claim back overpaid tax.
- Deductions for the full year: Some deductions (like mortgage interest) can be claimed for the entire year, not just the resident period.
How the M-form works
The M-form splits your tax year into two periods:
Period 1: Non-resident
Before your registration in the Netherlands, you are considered a non-resident. During this period, only Dutch-source income is taxable (for example, if you worked for a Dutch company remotely before relocating). Foreign income is generally not taxable in the Netherlands for this period.
Period 2: Resident
After registration, you become a Dutch tax resident. Your worldwide income becomes taxable in the Netherlands, subject to tax treaties. This includes employment income, investment income (Box 3), and any other income from anywhere in the world.
Important: double taxation
If you paid income tax in another country for the same year, you may be entitled to a foreign tax credit or exemption under a tax treaty. The Netherlands has tax treaties with over 90 countries. This is one of the most complex aspects of the M-form and where professional help pays for itself.
How to file the M-form
- Wait for the form to arrive: The Belastingdienst sends the M-form by post between March and May of the year after your arrival. It is sent to your registered Dutch address.
- Gather your documents: Collect your annual income statement (jaaropgave) from your employer, foreign income statements, bank statements for Box 3 assets, mortgage details, and any other relevant financial documents.
- Complete the form: The M-form is extensive — often 20+ pages. It covers Box 1 (income from work), Box 2 (substantial shareholding), and Box 3 (savings and investments) for both your non-resident and resident periods.
- Submit by the deadline: The standard deadline is July 1. You can request an extension online through MijnBelastingdienst or through a tax advisor.
Tip: request the form early
If you have not received the M-form by April, call the Belastingdienst (0800-0543 for English) to request it. You can also request it by letter. Do not wait until the deadline approaches.
Common deductions on the M-form
- 30% ruling benefit: If you have the 30% ruling, the tax-free allowance is applied to your Dutch earnings from the start date of your employment.
- Mortgage interest (hypotheekrenteaftrek): If you own property in the Netherlands, mortgage interest is deductible from Box 1 income for the resident period.
- Foreign tax credits: Tax paid in another country on the same income can be credited against your Dutch tax liability.
- Healthcare allowance: If your income qualifies, you can claim zorgtoeslag retrospectively.
- Moving expenses: Not directly deductible, but if your employer reimbursed moving costs under the 30% ruling, this is tax-free.
Should you hire a tax advisor?
The M-form is the one Dutch tax form where professional help is almost always recommended. Here is why:
- The form is paper-only — no online filing, no auto-fill, no error checking
- It involves two tax regimes (non-resident and resident) with different rules
- Foreign income and double taxation treaties are complex
- Mistakes can result in overpaying tax or delayed refunds
- Tax advisors typically find optimizations worth more than their fee
Expect to pay €250–500 for professional M-form filing. Many expat tax firms offer a free initial consultation to assess your situation.
Timeline and checklist
Year of arrival
Collect all income statements and receipts throughout the year
January – February (next year)
Receive your jaaropgave from employer and bank statements
March – May
M-form arrives by post. Engage a tax advisor if needed.
Before July 1
Submit the completed M-form or request an extension
4–12 weeks after filing
Receive your assessment (aanslag) and any refund
Frequently asked questions
What is the M-form?
The M-form (migratieformulier) is the Dutch tax return for the year you immigrated to or emigrated from the Netherlands. It covers a partial tax year — for example, if you arrived in June 2025, you file an M-form for June through December 2025. It is more complex than the regular C-form because it covers two tax regimes.
Do I have to file an M-form?
If you moved to the Netherlands mid-year and earned income during that period, you are generally required to file an M-form. Even if not required, filing is often beneficial because you may be entitled to a tax refund — especially if you started the 30% ruling during the year or worked for only part of the year.
When is the M-form deadline?
The M-form deadline is typically July 1 of the year following your arrival. For example, if you arrived in 2025, the M-form is due by July 1, 2026. You can request an extension until April of the following year. The Belastingdienst usually sends the M-form by post between March and May.
Can I file the M-form online?
No. Unlike the regular tax return (C-form), the M-form cannot be filed online through the Belastingdienst website. You must complete the paper form sent to you by post, or have a tax advisor file it on your behalf. This is one reason many expats use professional help for the M-form.
How much does it cost to have a tax advisor file my M-form?
Professional M-form filing typically costs between €250 and €500, depending on the complexity of your situation. Expats with the 30% ruling, foreign income, or Box 3 assets usually pay towards the higher end. The fee is often worth it — advisors typically find deductions and optimizations that exceed their fee.
Can I claim foreign income deductions on the M-form?
Yes. The M-form includes sections for worldwide income and foreign tax credits. If you paid income tax in another country for the same period, you can often claim a credit or exemption to avoid double taxation. This is where the M-form gets complex and professional help is most valuable.