If you live in the Netherlands and hold savings or investments, the Dutch tax system treats those assets under what is known as Box 3. Rather than taxing the actual return you earn, the system works with assumed returns on different categories of assets, and a threshold applies before tax is due. The rules have been revised in recent years, and further changes are planned, so the figures and method for 2026 may differ from what you remember or what older guides say.
For internationals, the practical points are straightforward. First, check whether you qualify as a Dutch tax resident, since that affects what you must declare. Second, gather clear records of your accounts, investments and any foreign assets, because the tax office may ask for them. Third, be aware that the 30 percent ruling and other expat arrangements do not automatically change how Box 3 applies to your assets. If your situation is complex, such as holding property or investments abroad, professional advice is worth considering.
What this means if you are learning Dutch or new in the Netherlands
Tax vocabulary is a useful part of settling in. Words like aangifte (tax return), vermogen (assets or wealth) and heffing (levy) appear often in official letters. Reading a short explainer in Dutch alongside an English one can build both your language skills and your confidence. Keep copies of documents and note key deadlines, and do not assume last year's rules still apply.