Among expats, one Dutch tax form has a near-mythical dread attached to it: the M-biljet, or M-form. You file it the year you move to or leave the Netherlands, and it’s genuinely more involved than the normal return. Here is what it actually is, why it’s different, and the words to take the fear out of it.
What the M-form is
As the Belastingdienst explains filing for the year of immigration or emigration, the M-form is the income-tax return for the year in which you immigrated to or emigrated from the Netherlands, the year you were a resident taxpayer for only part of the year. The M stands for migration.
The trigger is low: as tax explainers note about the M-biljet, if you lived here for even one month of the tax year, you were a binnenlands belastingplichtige (domestic taxpayer) for that part, and an M-form becomes mandatory for that year.
Why it’s harder than the normal return
The complexity is built in. As guides to the M-biljet for migration explain, it splits the year into a resident period and a non-resident period, each taxed differently, unlike the standard aangifte where you’re a resident all year.
It also long had a paper-only reputation, which didn’t help. The silver lining: the migration year often results in a refund.
How and when to file
The good news: it is no longer paper-only. You file it in Mijn Belastingdienst, choosing the return for people who lived outside the Netherlands for part of the year, with a DigiD or a recognised European login (eIDAS); tax advisers’ software can file it too. The calendar for the 2025 tax year, per the Belastingdienst and the government’s NederlandWereldwijd service: an invitation letter in February 2026, the online M return available from 1 May 2026, and no belastingrente (tax interest) if you file by 1 July 2026. Online filing is possible for the last five years, so a migration year you never filed for can still be done, and it is often a refund. If you cannot use DigiD, request the paper M form; it arrives within two weeks, and the form itself exists only in Dutch, which is where this vocabulary earns its keep.
Because of the split-year sums and possible foreign income, many expats use a belastingadviseur, but it can be done yourself.
The vocabulary
| Dutch | English |
|---|---|
| het M-biljet / M-formulier | the migration-year return |
| de immigratie / emigratie | immigration / emigration |
| belastingplichtig | liable for tax |
| binnenlands / buitenlands | resident / non-resident (for tax) |
| de teruggaaf | (tax) refund |
| de belastingadviseur | tax adviser |
Where it connects
The M-form is the entry point to a chain: what you owe afterwards is paid using the betalingskenmerk, and what you are owed comes back as toeslagen. If you freelanced during that first year, invoicing your first Dutch client covers the paperwork the return asks about.
The bottom line
The M-form (M-biljet) is the Dutch tax return for the year you immigrate or emigrate, when you were a resident taxpayer for only part of the year (even one month triggers it). It’s harder than the normal return because it splits the year, but it now files online via Mijn Belastingdienst and is due by 1 July, and it often yields a refund. Learn M-biljet, immigratie/emigratie and belastingplichtig, and the form’s scary reputation deflates into a manageable, often profitable, task.
Frequently asked questions
What is the M-form (M-biljet)?
The M-form is the Dutch income-tax return you file for the year in which you immigrated to or emigrated from the Netherlands, in other words, the year you were a resident taxpayer for only part of the year (the M stands for migration). If you lived in the Netherlands for even one month of the tax year, you were a domestic taxpayer for that part, which makes an M-form mandatory for that year.
Why is the M-form more complicated than a normal return?
Because it splits the year into two periods, the part you were a resident taxpayer and the part you weren’t, each taxed differently. That’s more involved than the standard return, where you’re a resident the whole year. Historically it could only be filed on paper, which added to its fearsome reputation. The upside: the year of immigration or emigration often results in a tax refund.
How and when do I file the M-form?
You can now file it digitally via Mijn Belastingdienst by selecting the return for people who lived outside the Netherlands for part of the year (tax-advisor software can also submit it electronically). The M-biljet must generally be submitted by 1 July. Because of the split-year calculation and possible foreign income, many expats use a tax adviser for it, but it can be done yourself.
When is the M-form due?
For the 2025 tax year the online M return opens in Mijn Belastingdienst on 1 May 2026, and filing by 1 July 2026 means no tax interest is charged. If you received a letter with a different date, that date applies; you can ask for an extension (uitstel) before the deadline. Returns for up to five past years can still be filed online.
Why does the M-form often give a refund?
Because the year is split. Payroll tax was withheld as if you earned your Dutch salary for a full year, while the return only taxes the months you were resident, and the tax credits and rate bands are applied to that shorter period. Expats who arrived mid-year with a job are very often owed money back, which is why the form is worth filing even when it is not strictly demanded.
