Ranked-choice ballots can become "inactive" or uncountable during tallying rounds in two ways: via ballot exhaustion, or ballot error.

“Ballot exhaustion” occurs when a ballot is no longer countable because all of the ranked candidates have already been eliminated. Exhausted ballots are incomplete, but not incorrect. In practice, ballots are most likely to be exhausted when a voter ranks only a small number of relatively unpopular candidates who are eliminated in the early rounds of tabulation. One study estimated that across four local elections using RCV, anywhere between 9.6-27.1 percent of the ballots cast were exhausted (Burnett and Kogan 2015).

Separately, about 5 percent of voters in RCV elections have filled out their ballots incorrectly. Ballot errors include selecting more than one candidate for the same ranking (”over-voting”), leaving a ranking blank (”skipping”) and selecting the same candidate for more than one ranking (”over-ranking”). Not all errors imply that ballots cannot be counted; over-voting is the most likely to result in rejection, while over-ranking is the least. About 10 percent of ballots containing errors are ultimately rejected, which amounts to only 0.5 percent of all votes. But even though this number is small in absolute terms, ballots in ranked-choice elections are still about 10 times more likely to be rejected due to improper marks than ballots in non-ranked elections (Pettigrew and Radley 2023).

To the extent that either ballot exhaustion or ballot errors reflect voter confusion about RCV, it may be temporary. More education (Donovan et al 2022), voter information (Boudreau et al. 2020) and experience with RCV (Neely and Cook 2008; Crowder-Meyer et al 2023) appear to increase voters’ understanding of this method of voting.

But in the meantime, ranked-choice ballots that go uncounted reinforce social inequalities. Minority voters tend to rank fewer candidates than white voters, which increases the odds their ballots are exhausted (Atkeson et al. 2024). Even in races where a minority candidate advances to the final round of tabulation, exhausted ballots are far more common in precincts and electoral districts with high concentrations of minority voters (McCarty 2024). Meanwhile, over-voting is more common in precincts with lower levels of educational attainment and lower median household incomes (Cormack 2024).