The 1 May income tax deadline (and how to get uitstel)
Master the 1 May income tax filing deadline: when the window opens, how to request an extension (uitstel), what happens if you're late, and tips to file early.
The 1 May income tax deadline is where theory meets reality for Dutch freelancers. Every year, you have a fixed window to file your personal tax return (the aangifte inkomstenbelasting). Miss it without a valid excuse, and you face penalties. File early, and you sleep better. This guide covers the deadline, how to ask for more time, and what to do if you've already missed it.
When does the filing window open and close?
The tax filing window is fixed every year:
The filing calendar
The Belastingdienst opens the filing system on 1 March each year. From that date you can log in to Mijn Belastingdienst with your DigiD and submit your income tax return. You must both file and receive confirmation by 1 May at the latest.
For tax year 2025, the deadline falls on 1 May 2026.
What happens if you miss the 1 May deadline?
If you don't file by 1 May, the Belastingdienst issues a formal notice giving you a few extra days to submit. If you ignore that, they move on to an automatic assessment (ambtshalve aanslag) based on their estimate of your income. This can go either way — they may assess you higher than your actual profit to be safe, or lower if they lack information. Either way, you lose control of the outcome.
Late-filing penalties
Filing after 1 May without authorization triggers a penalty. The amount varies, but it's worth avoiding. The faster you file, the lower your risk.
Requesting an extension (uitstel aanvragen)
If you know you'll miss the deadline, don't wait. You can request an extension — uitstel — from the Belastingdienst. This is a formal request to file late without automatic penalties.
How to request uitstel:
- Log in to Mijn Belastingdienst Zakelijk
- Navigate to your income tax return
- Look for the option to request an extension (usually a button or link like "Verzoek om uitstel")
- State your reason (illness, accountant delay, missing documents, etc.)
- Submit the request
The Belastingdienst typically grants uitstel if you have a reasonable explanation — accountant backlog, missing invoices, illness, or documentation from a third party that wasn't ready in time. You won't get infinite time, but a 4–6 week extension is common.
Once you have uitstel, you receive a new deadline. File before that date and you're safe.
Let ZZP Belasting do the maths
Automatic BTW returns, income-tax forecasts and depreciation — from the invoices you already have.
Try it freeFive practical tips to meet the deadline
1. Use the automatic pre-fill. The Belastingdienst usually pre-fills the major items from previous years and third-party data (bank interest, pension contributions, etc.). Review and update these — don't just submit them as-is.
2. File from mid-April onward. Don't wait until 30 April. File by mid-April and avoid the rush. Any issues are easier to fix with time left.
3. Keep your bookkeeping live. If you update your business profit continuously through the year (not just in April), filing day is just entering a number you already know. See calculating your business profit for the structure.
4. Have your accountant or bookkeeper ready early. If you use external help, brief them in February. Ask for draft figures by mid-April so you have time to review and file.
5. Use ZZP Belasting to forecast your profit. The app tracks your income and deductible costs throughout the year and gives you a tax forecast. You'll know your profit number well before 1 May, so no last-minute scrambling.
What you'll actually declare
On your income tax return you declare:
- Profit from your business (winst uit onderneming) — your turnover minus deductible business costs
- Entrepreneur deductions — zelfstandigenaftrek, startersaftrek (if eligible), and the MKB-winstvrijstelling
- Other income — any salary if you also work in employment, rental income, etc.
- Deductible items — mortgage interest, donations, childcare costs, pension premiums, etc.
A worked example: you made €60,000 revenue, your business costs were €15,000, so your profit is €45,000. You claim the zelfstandigenaftrek (€2,470 in 2025), reducing your taxable income to €42,530. On that you pay income tax; you also get the MKB-winstvrijstelling (12.7% exemption) applied automatically. Your actual tax bill is lower because of those deductions.
Read income tax for the self-employed for the complete walkthrough.
If you're already late
If you missed 1 May and didn't request uitstel:
- File immediately anyway. Filing late without permission is worse than filing very late. The sooner you submit, the sooner you can work on a resolution.
- Request uitstel retroactively. Contact the Belastingdienst and explain. If there's a valid reason, they may cancel the automatic penalty.
- Pay any tax you owe. If your return shows you owe money, pay it quickly. This reduces interest (rente) accrual.
- Check for an automatic assessment. Search your Mijn Belastingdienst account for any provisional or final assessment the Belastingdienst may have already issued. If you disagree, you have 6 weeks to lodge a formal objection (bezwaar).
Frequently asked questions
Do I need an accountant to file my return?
What if I haven't finished my bookkeeping by 1 May?
Can I file a provisional return and update it later?
The 1 May deadline is firm, but it's not a trap. Build a buffer: file by mid-April if you can, keep your records live, and request uitstel early if you need it. The key is not waiting until 30 April when the system is congested and problems are hardest to fix. Plan ahead and the deadline becomes routine.