Local turnout has declined in many European countries, posing challenges to the inclusiveness and representativeness of elections. One response proposed to address this challenge are franchise extensions to new groups of voters. Distinguishing between horizontal extensions to non-national EU-citizens and vertical extension to 16- to 18-year-olds, we analyse their effects on voter turnout in the context of German local council elections. The country’s federal system enables us to analyse the effects on voter turnout in 13 states from 1978 until 2019. We find that the horizontal franchise extension is associated with a subsequent drop in overall turnout at German local council elections. By contrast, vertical franchise extensions do not affect turnout. The findings temper expectations concerning the ability of local franchise extensions to boost democratic legitimacy via increased participation.