How does losing one’s right to vote again after having been eligible to vote before affect political fundamentals such as political efficacy? We draw attention to the hitherto neglected phenomenon “temporary disenfranchisement,” which, for instance, occurs regularly in states that extended the franchise to underage citizens in some but not all elections. If an election with voting age 16 is closely followed by an election with voting age 18, underage voters who are eligible for the former will have no right to vote in the latter. Using original panel data on young citizens in Germany and a differences-in-differences design, we find that temporary disenfranchisement results in a decrease in external efficacy, which remains even after regaining eligibility. Our findings highlight an important side effect of selective voting rights extensions and bear insights that are relevant to other cases of temporary disenfranchisement due to residential mobility, citizenship, or felony disenfranchisement.