Are payments related to a study loan deductible in my Dutch income tax return?
Repayments of a loan are never deductible. The costs related to a loan are only deductible if the loan was used for the purchase (or renovation) of your main residence or if the loan is arranged by a business for business purposes. The loan falls in the so called Box 3 in which savings and investments are taxed and will there reduce the taxable base. There are special rules for employees with the 30% ruling who can be partially exempted from declaring Box 3 income and as such the loan will not lead to a (extra) benefit in that situation.