Top-up pension plans were introduced in 2015 as a consequence of the implemented maximum pensionable salary. In this thesis, the intertemporal investment problem for a net pension top-up plan participant is studied. A stylized framework is developed that captures the main features of the top-up plan. These main features include the conversion of accrued financial wealth into a life annuity subject to a particular funding ratio surcharge at retirement. Additionally, the implicit presence of guaranteed pension benefits as well as classic human capital are taken into account. Within this framework, a life-cycle investment strategy is determined that best serves the expected utility maximizing participant. In case the surcharge equals the actual funding ratio at retirement, closed-form solutions are provided under a certain set of assumptions.