Dutch tax filing season: what to do now

The calendar at a glance

• 1 March: Mijn Belastingdienst opens for the prior tax year. Most pre-filled fields are populated by this date.
• End of February:Your employer issues your jaaropgaaf for the prior year. Save the PDF; you'll cross-reference it during filing.
• 1 May: Standard filing deadline for residents (P-form).
• 1 July: The Belastingdienst aims to have processed timely returns by this date if filed before 1 April. Refunds for timely returns typically land within 6 weeks of the aanslag.
• 1 September: The free extension deadline (request it before 1 May).
• 1 November:Voorlopige aanslag election for next year — request now to spread next year's expected refund or liability across monthly payments.
• May the year after:Adviser's collective extension (uitstelregeling) deadline if you filed through a registered tax consultant.

Things to gather before you start

• Jaaropgaaf from every Dutch employer for the tax year (gross, loonheffing, holiday allowance, RSU/options income).
• Foreign payslips and year-end forms if you had any non-Dutch income (W-2, P60, Lohnabrechnung, etc.). Required if you arrived or left mid-year.
• Bank balances on 1 January for every account you held — Dutch and foreign. The Belastingdienst pre-fills Dutch balances; you need foreign ones.
• Brokerage portfolio value on 1 January for every broker, plus crypto holdings (DEGIRO, IBKR, Trading 212, Coinbase, etc.).
• Mortgage statement showing total interest paid in the year and outstanding principal at 31 December.
• WOZ assessment for your home, used for the eigenwoningforfait.
• Healthcare receipts above the threshold for specific care (chronic condition expenses, mobility aids, etc.).
• ANBI donation receipts for charitable gifts.

File yourself, or get help?

Online P-form for a clean year (one Dutch employer, no mortgage, no foreign accounts) takes ~30 minutes once you have the paperwork. Most pre-filled fields are already correct; you're mainly checking the numbers.

Get help if any of these apply:

• It's your migration year (M-form is paper-based).
• You have foreign income, employer, or self-employment.
• You have RSUs or options vesting from a non-Dutch payroll.
• Multiple Dutch employers in the same year.
• Foreign property, rental income, or substantial holdings.
• You're on the legacy partial-non-resident election.

Adviser fees range from €150 for a simple P-form to €600+ for an M-form with foreign-income complexity. For first-year arrivals, paying once is almost always worth it: errors here propagate forward, and the M-form is genuinely fiddly.

Voorlopige aanslag: get refunds monthly instead of yearly

If you have predictable refund-driving deductions (mortgage interest, hypotheekrenteaftrek being the big one), you can request a voorlopige aanslag and have the expected refund paid monthly through the year instead of as a lump sum at filing time. Useful for cashflow planning when the refund is large. Apply via Mijn Belastingdienst → Voorlopige aanslag.