2026/07/21 by Gonzalo Contreras, Mauricio Morales Quiroga
paper · doi:10.1177/00323217261460721
Compulsory voting (CV) reliably raises turnout, but its effects on invalid ballots and the inequalities these produce are less well understood. Chile’s return to CV in 2022 provides a rare within-country test of how the shift from voluntary to compulsory participation reshapes invalid voting and what this produces in the context of shifting inequalities. We analyse the last local elections held under voluntary voting (VV, 2021) and the first under CV (2024) across all 345 municipalities, exploiting concurrent contests held under distinct electoral rules. Our central finding is that CV shifts inequality from participation to vote validity, with rates of invalid voting varying across majoritarian and proportional elections. Specifically: (1) invalid voting increased substantially under CV, though valid votes for parties and candidates also rose; (2) the entry of new voters is associated with a shift from abstention under VV to invalid ballots under CV; (3) ballot size is more strongly associated with invalid voting under CV in proportional than in relative-majority systems; (4) poverty is unrelated to invalid voting under VV but becomes significant under CV, especially in the capital; and (5) rurality is negatively associated with invalid voting under CV but not under VV. These results contribute to debates on whether CV corrects or displaces class bias in participation, on the structural determinants of invalid voting, and on how electoral system type conditions invalid ballot rates under compulsory participation.