Who must file
Anyone with winst uit onderneming, so a sole trader, a zzp'er or a partner in a vof, files an income tax return covering both a private and a business part, and must file it digitally. A BV or NV files vennootschapsbelasting instead.
Tax year and deadline
Calendar year. The return is due by the date in your aangiftebrief, in practice 1 May. Ask for uitstel before 1 May and you have until 1 September; a request arriving later is refused. An accountant can obtain a longer collective extension.
Filing step by step
- Log in to Mijn Belastingdienst with DigiD; the return is largely pre-filled and you add the business section.
- Or file from commercial bookkeeping software that submits directly.
- Or have an accountant or tax adviser file it, which also opens the collective extension.
- VAT returns go through the separate business portal, not this one. Paper filing is not allowed for an ondernemer.
Penalties for filing or paying late
An income tax return that does not arrive by the date on the aangiftebrief first brings a reminder, then an aanmaning giving 10 working days. A return filed after that brings a verzuimboete of EUR 469, which can rise to EUR 6,709 for repeated lateness; the legal maximum for a missing or late return is EUR 6,709 (art. 67a(1) AWR). Without any return, the Belastingdienst estimates the income and issues an assessment with a fine, and can stop payment of toeslagen. An intentional failure can be fined up to 100% of the base (art. 67d AWR). A late return also costs belastingrente, which is 5% a year from 1 January 2026.