Missing the deadline for your M-form is fixable: the Belastingdienst still wants the return, and a migration year very often produces a refund because wage tax was withheld as if you worked the full year. If you were never invited to file (no aangiftebrief), the general rule for the income tax return applies: you may file voluntarily up to five years back to claim a refund. If you did get an aangiftebrief and did not respond in time, the Belastingdienst works through a reminder and then a formal demand with a new, shorter deadline, the same process it uses for the income tax return in general. Taxmo files the M-form for tax year 2025 directly to the Belastingdienst through Digipoort, even when you are late, from €129 incl. VAT.
Yes. A missed date is not a closed door. The Belastingdienst accepts a return that arrives after the official date, and a migration year very often still produces a refund, because wage tax was withheld as if you worked the full year. If you were not required to file, meaning you never received an aangiftebrief, the general rule for the income tax return applies: you may file voluntarily up to five years back to claim a refund. For the M-form itself, Taxmo currently only files tax year 2025; for an older migration year you go through Mijn Belastingdienst.
If you received an aangiftebrief and did not respond in time, the Belastingdienst takes two steps before a penalty follows, for the income tax return in general: first a reminder, asking you to still file, and if that also goes unanswered, a formal demand (aanmaning). From the date on that demand you have 10 working days to get the return in. If it still has not arrived after that, a late-filing penalty (verzuimboete) follows; as currently published, the Belastingdienst states €469 for a first late filing, rising to €6,709 for repeated late filing. Always check the current amount on belastingdienst.nl, since penalty amounts are set by law and can change. The M-aangifte is not mentioned separately on that page; it is the standard procedure for the income tax return, of which the M-aangifte is one form.
An extension for the tax return is granted until the date your return must arrive at the Belastingdienst, the date stated in your aangiftebrief, not a fixed calendar date. For the M-aangifte you request that by signing and mailing the 'Aanvraag uitstel aangifte inkomstenbelasting' form, or by calling the BelastingTelefoon Buitenland. Once the date your return had to arrive has already passed, you can no longer request an extension; for the regular 2025 income tax return, for example, that date is 1 May 2026. Check belastingdienst.nl for the date and method that apply to your M-aangifte.
Even late, you go through the same steps in Taxmo as any migration year: a few screening questions first, then the wizard through your move, your Dutch and foreign income, your own home, deductions, relief from double taxation and the pension claims an emigrant must report. Taxmo currently files the M-form for tax year 2025 directly; for an earlier migration year you file yourself through Mijn Belastingdienst. Before you pay, the return is checked against the rules the Belastingdienst applies, so you only pay once it is ready to file. Any late-filing penalty from the Belastingdienst itself, if you already received a formal demand, is separate from that and is paid directly to the Belastingdienst.
The M-form on Taxmo, even when you are late, is for anyone who moved to or from the Netherlands once in the year, with income from employment, benefits, pensions, other work and an own home, also when they lived in more than one country abroad, with a fiscal partner (Standard) or Plus (€159 incl. VAT) adds aanmerkelijk belang (box 2), savings and investments (box 3) and business profit (Plus). Not yet supported: your partner's own residence in Belgium, Suriname or Aruba with Dutch-taxed income, or their qualifying foreign taxpayer statement, moving to and from the Netherlands in the same year (the paper M-biljet covers that) and green investments combined with a period not insured for the Zvw, or box 3 assets already taxed abroad while you lived in the Netherlands. The screening questions tell you before anything else; nothing is charged for a situation that cannot be filed.