Dutch income tax assessments, tax payments and tax refunds

Generally, Dutch income tax is only due or refundable after the issuance of a tax assessment.

The tax assessment specifies the amount of income tax due or refundable and the payment due date.

The law distinguishes various kinds of income tax assessments:

• preliminary assessment (in Dutch: 'voorlopige aanslag');
• final assessment (in Dutch: 'definitieve aanslag');
• additional assessment (in Dutch: 'navorderingsaanslag');
• Ex-officio assessment (in Dutch: 'ambtshalve aanslag');
• protective assessment (in Dutch: 'conserverende aanslag').

The crucial function of an assessment is the formalization of a tax debt (positive or negative).