10 most frequent mistakes made when filing a Dutch tax return

Filing your Dutch tax return may seem straightforward, especially with the pre-filled online system. Yet every year, the same mistakes cost taxpayers money and unnecessary stress. Missed refunds, late filing, and wrong numbers can have a big financial impact.

Here are some classic mistakes that people make. 

1. Filing after the deadline

The standard deadline for filing your Dutch income tax return is May 1. Taxpayers can request an extension. If you submit your tax return after May 1 and you owe tax, the Belastingdienst will usually charge tax interest, even if you were officially granted an extension, which often comes as a surprise to taxpayers.

2. Choosing the incorrect tax return form

The incorrect selection of the applicable income tax return form (P-, M-, or C-form) is a common issue, particularly in cases involving migration or cross-border income and can result in incomplete or incorrect tax reporting.

3. Not filing because the income feels “too small”

Side jobs, part-time work, or internships often go undeclared because the income feels insignificant. In the Netherlands, however, all income must be reported, regardless of the amount.

Filing does not always mean paying more tax. In fact, especially with lower income, you may be entitled to a refund due to tax credits or withheld payroll tax. You can submit tax returns for up to five previous years.

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4. Failure to declare foreign income

Taxpayers often assume that income that’s earned abroad, already taxed in another country, or received on foreign bank accounts, does not need to be reported in the Netherlands. However, Dutch tax residents are generally required to declare their worldwide income, including foreign income, pensions, investments, and assets.

While double taxation is usually avoided through tax treaties or tax credits, the income itself must still be reported correctly. Not declaring can lead to reassessments, penalties, and interest charged by the Belastingdienst. 

5. Not filing together with a fiscal partner

If you have a fiscal partner (e.g., a spouse or registered partner), filing together can significantly affect your final tax result. Certain deductions and income can be allocated between partners in a tax-efficient way.

For example, individuals have a tax-free allowance for assets up to €57.000. When filing together, this threshold increases to €114.000 for joint assets. When filing separately without coordination, deductions and allowances are often missed or applied incorrectly. 

6. Making one of these mistakes after a divorce or separation

Divorce often leads to tax complexities that are underestimated. We regularly see mistakes in tax returns filed after a separation, especially in these areas:

Own home

Who continues living on the property? Who pays the mortgage? Who deducts mortgage interest? Incorrect application is common, particularly regarding the two-year rule for mortgage interest deduction after separation.

Alimony

Only spousal alimony is deductible for the payer and taxable for the recipient. Child support is not deductible. When one party deducts amounts that the other does not declare, this creates questions for the tax authorities. Housing-related contributions can also sometimes qualify as alimony but are often overlooked.

Divorce covenant

Agreements in the divorce covenant are frequently incomplete or incorrectly implemented in the tax return. This can lead to incorrect declarations on both sides.

7. Using the wrong WOZ value

The WOZ value is the official property valuation used for tax purposes. For the 2025 tax return filed in 2026, you must use the 2024 WOZ value. Using the wrong reference year is a common mistake, especially for homeowners who recently moved or received a new WOZ assessment.

8. Making errors with home ownership

Errors related to home ownership are among the most common issues in Dutch tax returns. Taxpayers make mistakes in the application of the eigenwoningforfait, the deductibility of mortgage interest, and the misclassification of housing-related expenses.

Risks arise in complex situations such as refinancing, temporary rental, partial sale, divorce, or purchasing a new home after selling another (bijleenregeling). Misclassification between Box 1 and 3, and failure to apply transitional rules, can result in over- or underpaying tax. 

9. Forgetting foreign dividend withholding tax

Expats often hold investment accounts abroad. What is often overlooked is that withholding tax on foreign dividends can often be offset or deducted in the Netherlands under applicable tax treaties. Not including this can mean paying more tax than necessary.

10. Not using available deductions

One of the biggest mistakes is not using the deductions or falsely claiming deductions without checking the criteria first. These include:

• Medical expenses (only what is not covered by your mandatory excess (eigenrisico) and not reimbursed by insurance)
• Charitable donations
• Commuting costs
• Mortgage interest
• Annuities and supplementary pension contributions
• Spousal alimony
• Weekend expenses for disabled dependents 

If you are an entrepreneur, additional deductible expenses may include:

• Advice on the viability of the business
• Registration with the Chamber of Commerce
• Rent for business premises
• Office and workplace furnishings
• Maintenance costs
• Insurance
• Business travel using public transport

Tip: research all deductions and their criteria to make the most of your tax return.