Belgium’s first capital gains tax year closes in seven weeks.
Since 1 January 2026, Belgian residents pay a 10% tax on capital gains from financial assets. What looked straightforward on paper became a moving target in practice:
🔹 The law was only adopted in April 2026.
🔹 Belgian bank withholding only started on 1 June – gains realised before that were not subject to withholding.
🔹 Clients could opt out of withholding and declare their gains themselves.
🔹 Gains accrued before 2026 are protected through a step-up mechanism.
The result: for income year 2026, many clients will have a mix of withheld and non-withheld gains – and they’ll need clear figures for their 2027 tax return.
This is where tax reporting stops being a formality. A report that shows what has to be withheld, what hasn’t, and why, saves clients and advisors a lot of questions.
How are you preparing your Belgian client base for the first reporting cycle?
