Based on the Surpreme Court decision (in fact 2 decisions) the actual result from investments should be taxed rather than the deemed (Box 3 method) result.

What needs to be considered as actual result
To make life a bit easier, we created the below list of items that may be relevant for the determination of your actual result from investments. Depending on which Box 3 items are relevant. Note that your principal residence and the mortgage loans which are linked to the principal residence are not considered as part of your wealth for tax purposes.

The following information may need to be shared per account/item:

Bank/savings (Dutch and foreign)
- Interest received 
- Exchange rate proceeds  

Investments (Dutch and foreign)
- Value on January 1
- Value on December 31
- Value of cash deposits in the year 
- Value of cash withdrawals in the year
- Amount of gross dividend
- Amount of gross interest

Claims 
- Value of the claim on January 1
- Calue of the claim on December 31
- Repay installments received
- New loans provided
- Interest received

Crypto
- Value on January 1
- Value on December 31
- Value of cash deposits in the year 
- Value of cash withdrawals in the year

Debts
- Balance on January 1
- Balance on December 31
- Interest paid

Property
- Value on January 1 (WOZ value for Dutch property)
- Value on December 31
- Rental income
- Purchase price (if applicable)
- Purchase costs (if applicable)
- Sale price (if applicable)
- Sale costs (if applicable)

Dutch property
- WOZ value on Jan 1 of the year prior to concerning tax year
- WOZ value on Jan 1 of the concerning tax year
- Rental income
- Investments registered with the municipality
- Purchase price (if applicable)
- Purchase costs (if applicable)
- Sale price (if applicable)
- Sale costs (if applicable)

Debts related to investment property
- Mortgage loans
- Mortgage interest paid
- Mortgage costs paid


On the website of Belastingdient.nl you can find a blue box regarding "Box 3: brief gekregen om uw werkelijk rendement door te geven?" 

Here you click on > Vul het formulier in

Follow the steps to see which information needs to be submitted and provide all the relevant data.