Property in Sri Lanka
A house, flat or land in Sri Lanka counts in your Box 3 wealth at its value on 1 January. Under the treaty Sri Lanka may tax that property, and the Netherlands exempts the share of Box 3 tax that falls on it.
So you usually pay no Dutch tax on it, but you still have to declare it. It also counts when the tax-free allowance is spread over your assets, so your other wealth can be taxed slightly more.
Bank accounts and investments in Sri Lanka
Savings, deposits, shares and funds in Sri Lanka stay taxable in Dutch Box 3, just like assets here. The Netherlands is your country of residence and keeps the right to tax them.
If Sri Lanka withheld tax on interest or dividends, it's credited against the Dutch tax on that slice, up to that Dutch tax and the rate the treaty allows.
Converting and declaring
Convert amounts to euros at the exchange rate on 1 January of the tax year. Keep a year-end statement from the bank or broker and a valuation of any property.
Many countries automatically share account information with the Belastingdienst. If you left foreign assets out in earlier years, correcting it voluntarily usually means a lower fine than if the Belastingdienst finds it first.
Money from family in Sri Lanka
Gifts from parents or relatives living in Sri Lanka are not subject to Dutch gift tax, unless the giver is a Dutch national who left the Netherlands less than 10 years ago. From the next 1 January the money does count in your Box 3.
Keep calculating
General information based on Dutch treaty practice for Box 3. Your own situation may differ; have foreign assets checked by an adviser if in doubt.