The tax year in the Netherlands is the calendar year. If the tax authorities have information that you will have to pay income tax or if you have claimed a refund in previous years or if you received a provisional refund the tax authorities will send you an invitation to file a tax return. If you don’t get one and you expect a refund or know that you do have to pay income tax then you must request a form yourself.
P form : tax return for private individuals
E form : same as a P form but with less questions
T form : tax refund form
C form : for foreign residents with income from the Netherlands
M form : for the year of migration
O form : tax return for business owners and freelancers
For more info see our Brochure: Filing a tax return in the Netherlands.