Pot one: VAT
The VAT on your invoices is money you collect for the Dutch Belastingdienst. Set it aside the moment your customer pays, and subtract the VAT you paid yourself on business costs; you pay the difference with your VAT return, for most entrepreneurs per quarter. Anyone who treats this VAT as turnover runs short of money at the end of the quarter.
If you fall under the small business scheme (KOR), you charge no VAT and this pot is empty. How the rates and the return work is in the guide on VAT in the Netherlands.
Pot two: income tax
You don't calculate income tax on your turnover, nor on your full profit, but on your taxable profit: your profit minus the self-employed deduction (€1,200 in 2026, if you meet the hours criterion), in your first years the starter's deduction (€2,123), and then the 12.7% SME profit exemption. In 2026 the box 1 brackets for those below state pension age apply: 35.75% up to €38,883, 37.56% from €38,883 to €78,426, and 49.50% above that. The general tax credit and the labour tax credit come off the result, and they can lower it considerably.
That is why a fixed percentage of your turnover works poorly: the credits phase out as you earn more, and a second income from employment pushes your profit into a higher bracket. Better to calculate it on your own figures, and to do so again during the year, because the tax applies to the whole year and not per month.
Pot three: the Zvw contribution, and how to spread
As an entrepreneur you pay the income-related contribution under the Health Insurance Act (Zvw) yourself to the Dutch Belastingdienst, separately from your income tax. In 2026 it is 4.85% of your income, up to a maximum contribution income of €79,409 — so at most about €3,851. You get a provisional assessment of its own for it, usually based on an earlier year; if you earn less than that estimate, you can change it online.
For income tax you can request a provisional assessment yourself; the Belastingdienst recommends it to starting entrepreneurs who expect a profit. You then pay the current year in at most eleven monthly instalments, or at once, instead of all at once next year after your return. You base the amount of that assessment on your expected profit — which brings you back to pot two.
What the software calculates for you
In booxx you'll find the IB & Zvw reservation screen under Reports. It calculates from the profit in your books: first the self-employed and starter's deductions, then the SME profit exemption, then the brackets, then the general tax credit and the labour tax credit, and separately the Zvw contribution up to the maximum. You fill in what doesn't follow from the books yourself: whether you meet the hours criterion, whether you are a starter, whether you lived in the Netherlands all year and what other income you had, such as wages.
If you choose part of the year, the screen first extrapolates your profit to a full year, calculates the tax on that and shows the share that belongs to the months that have passed — so the brackets and credits are right in April too. It is an indication to reserve against, not a tax return: it leaves out box 3, a tax partner and your own home. The software works in Dutch, English, Polish, Hungarian and Romanian, and you can try it for 90 days without a payment method.
Updated October 2, 2026. General explanation of the Dutch rules, not tax advice — for your own situation, decide together with your accountant or the Dutch Tax Administration.