The issuance of an additional assessment (navorderingsaanslag)

Once a tax year has been closed through the issuance of a final income tax assessment, the Dutch tax office can still re-open this year if a new fact has come to the attention of the tax inspector. Based on this new fact, the Dutch tax office will impose and levy an additional assessment (in Dutch: 'navorderingsaanslag'). The requirement of a 'new fact' does not apply if the taxpayer is of bad faith. A new fact is also not required if the tax amount levied on the final assessment is at least 30% or more lower than it would have been if the inspector had had all relevant information.

The right to levy additional tax assessments (statute of limitations) expires in most cases 5 years after the end of the tax year. This 5 year term is extended with the extension granted for filing the income tax return. If the income to which the additional assessment relates to, originates from abroad, this term can be extended to 12 years.

The amount of the additional assessment can be increased with interest and penalties.

The penalty for intentionally not declaring income can be as high as 300% of the tax due.

Special rules apply for taxpayers which voluntarily report the previously non-declared foreign income before the tax office becomes aware of the this fact or it can reasonably be expected that they will shortly become aware of this fact. This is in fact a form of tax amnesty (in Dutch: 'inkeerregeling') which provides for reduced penalties and grants the taxpayer immunity for criminal prosecution.