1. A failsafe ballot provided to a voter whose eligibility for a regular ballot cannot be immediately determined. The ballot may be counted or further processed depending on state law.
Source: Election Terminology Glossary - Draft, National Institute of Standards and Technology (NIST), https://pages.nist.gov/ElectionGlossary/; Pilot Implementation Study of Risk-Limiting Audit Methods in the State of Rhode Island, Rhode Island RLA Working Group, https://www.brennancenter.org/sites/default/files/2019-09/Report-RI-Design-FINAL-WEB4.pdf
2. A ballot cast by a voter whose eligibility to vote is disputed by an election official. Standards for counting provisional ballots vary significantly among the states.
Source: COUNTING VOTES 2012: A State by State Look at Voting Technology Preparedness, Verified Voting Foundation, Rutgers School of Law - Newark Constitutional Litigation Clinic & Common Cause Education Fund, https://countingvotes.org/sites/default/files/CountingVotes2012_Final_August2012.pdf
3. Ballot provided to individuals who claim they are registered and eligible to vote but whose eligibility or registration status cannot be confirmed when they present themselves to vote. Once voted, such ballots must be kept separate from other ballots and are not included in the tabulation until after the voter’s eligibility is confirmed. In some jurisdictions this is called an affidavit ballot.
Source: Glossary of terms database, U.S. Election Assistance Commission, https://www.eac.gov/glossary/