We would advise you to look over your “M form” based income tax assessment for 2015, as the Tax and Customs Administration may inadvertently have failed to factor your “deduction taxed elsewhere” into its calculations. Although the tax service is making a concerted effort to redress this (possible) omission on its part, it can’t do any harm to perform a check of your own.
Dutch version: Controleer uw aanslag over het M-biljet 2015