This paper exploits unexpected regional changes in fees to uncover the causal effect on the duration of study and completion probabilities for an entire country. The empirical analysis relies on a novel empirical framework that merges difference-in-difference estimation with duration analysis to exploit a natural policy experiment, namely the introduction and terminationof fees for university studies in several German states. This strategy allows uncovering effects of fees on the intensive margin, while holding constant extensive margin responses such as changes in the composition of the student body or migration responses that occur due to fees.We find that even modest fees have large and significant impacts on study duration and will also examine if the private costs paid by students are recovered through pubilc savings due to students studying faster.