What is 'reserveringsruimte'?

"Reserve space" is annual room from the past that you have not used. Suppose you had €10,000 annual room last year but you did not contribute anything for your pension. That €10,000 does not disappear: you can still use it this year, on top of this year's annual room. You can use unused annual room up to 10 years back, with a maximum of € 42,108 in 2025. Useful for years when you have a bit more to spend.