As a freelancer you are responsible for your own taxes. Some get an accountant to this but there is not much to it if you break it down. Here we discuss the VAT declaration, BTW in dutch.

VAT are the taxes you charge on the products or services you deliver. Other companies do the same on the products you buy as a business. Every 3 months you pay these taxes you charged minus the VAT you payed to other businesses.

For all rules around this VAT declaration visit the site of the Dutch Tax Office.

Example

Let’s say you work as a frontend developer and you just started a new job in October. Every month you worked you send an invoice on the 10th of the next month when your manager approves your hours. In your first week you notice you need a new keyboard so you buy a new one. 

VAT Declaration

Obtained  | invoice over October | 10.000 | VAT 2.100
          | invoice over November| 10.000 | VAT 2.100

Payed     | keyboard             |    100 | VAT   -21

total (to be payed):                             4179

The invoice over December has date 10th of Januari. So it is not included. Also the invoice over November could not be payed yet but is included due to its invoice date.

Moreover there are some services where no VAT is charged. In general all insurances are free of VAT.