Political participation is the backbone of democracy. One measure to increase voter turnout in vote-by-mail systems is prepaying postage. Previous studies investigated the effect of prepaid postage and found that it significantly increases turnout.

Using an original data set covering all national direct democratic votes in 1893 Swiss municipalities from 2005 to 2023, They replicate earlier studies and investigate temporal as well as contextual variation. They find that the effect of prepaid postage on turnout is contingent upon both time and municipal characteristics: 1) postage starts to increase turnout only after three to five years. 2) Abolishing prepaid postage reverses the increase in turnout. 3) The effect is larger in municipalities with more post boxes and a greater average distance to the office of municipal authorities. The evidence from our study suggests that prepaid postage cannot be viewed as a one-size-fits-all solution.

In this exploration, they see that absentee/mail-ballot rejection rates dropped significantly in 2020 compared to 2016, dropping the most in states that had previously erected high barriers to the use of mail ballots. Pre-processing laws and deadlines for the receipt of mail ballots didn’t seem to have much effect on rejection rates. Policy choices that did seem to matter were requiring multiple forms of identification with a returned ballot, which significantly increased rejection rates, and allowing ballots with administrative deficiencies to be “cured,” which significantly decreased rejection rates.