In a Chamber letter the State Secretary for Finance announced that the form for reporting actual returns in box 3 will (probably) not be made available until June 2025.
Form OWR
In our article What should I do following the box 3 judgements? write that you can already take stock of what actual return you have achieved with your assets in box 3. This concerns the years 2021 to 2023 (the 2024 return cannot yet be determined, of course).
Then again, you don't have to be in too much of a hurry to do so. The Inland Revenue will not make the form OWR (that abbreviation stands for Opgaaf Werkelijk Rendement) available until June 2025 (provided the draft schedule is realised). The main reason why this has to take so long is that the automated processing of these forms is yet to be sorted out.
The final assessments for the years 2021 to 2024 can then be determined from Q4 2025, according to the draft schedule.
Clarification
In the Parliament letter, we also find an (initial) interpretation by the Ministry of Finance/Taxation of the judgments delivered by the Supreme Court on 6 and 14 June 2024. To a large extent, this concerns cases that the Supreme Court described as such in the judgments.
Finance describes that the starting point for enjoying the return is the cash system. This will be relevant, inter alia, for bank accounts on which interest is credited by the bank on 1 January following the year for which the interest is calculated.
There are a number of issues that Finance is going to investigate further. These include the question of how to tax the own use of a property. And the question of how to determine value development when a property is bought or sold during a year.