Why you work back from your net
An hourly rate copied from a colleague or a job site says nothing about what you keep. Your costs, your hours and your tax decide that. So the calculator starts from the amount you want to keep each month, finds the profit at which you have exactly that net after income tax and the Zvw contribution, adds your costs and divides the turnover by your billable hours.
Because the tax is not a fixed percentage — the brackets rise and the tax credits phase out — the profit you need grows faster than your net. Going from €3,000 to €3,500 net a month takes about €10,064 more profit a year in the example above, not €6,000.
Billable hours are not your working hours
For the hours criterion every hour you spend on your business counts, including bookkeeping and finding clients. For your hourly rate only the hours a client pays for count. Many freelancers bill twenty to thirty hours of a forty-hour week; the rest goes on sales, travel and admin. Calculate with forty billable hours and your rate comes out too low.
Count your weeks honestly too: holidays, public holidays, sickness and quiet spells between assignments. Someone who counts 44 weeks and works 38 misses more than a seventh of their turnover.
What comes on top
As an employee your employer contributes to your pension and you are insured against incapacity for work. As a freelancer you arrange that yourself, from your own money. Enter those amounts under provisions and the calculator includes them in your profit and your rate. VAT comes on top separately: your client pays it and you pass it on, so it is not part of your turnover.
In booxx you see during the year how your turnover, costs and profit compare with what you need, and the IB & Zvw reservation screen works out what to set aside for the assessment. You can try it for 90 days without a payment method, in Dutch, English, Polish, Hungarian and Romanian.
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.