Incentives for registering to vote or voting
From SOS Voter Registration Guide: Offering Incentives for Registering Voters
Federal law makes it unlawful in an election in which there is a federal contest on the ballot (e.g., President, U.S. Senate, U.S. Representative) to knowingly and willfully pay, offer to pay, or accept payment for registering to vote or for voting. (52 U.S.C. §10307(c).) Violations are punishable by a fine up to $10,000 or imprisonment for up to five years, or both. Any type of incentive is considered “payment,” even things as seemingly innocent as cookies or admission to an entertainment event.
52 U.S.C. §10207(c) False information in registering or voting; penalties
Whoever knowingly or willfully gives false information as to his name, address or period of residence in the voting district for the purpose of establishing his eligibility to register or vote, or conspires with another individual for the purpose of encouraging his false registration to vote or illegal voting, or pays or offers to pay or accepts payment either for registration to vote or for voting shall be fined not more than $10,000 or imprisoned not more than five years, or both: Provided, however, That this provision shall be applicable only to general, special, or primary elections held solely or in part for the purpose of selecting or electing any candidate for the office of President, Vice President, presidential elector, Member of the United States Senate, Member of the United States House of Representatives, Delegate from the District of Columbia, Guam, or the Virgin Islands, or Resident Commissioner of the Commonwealth of Puerto Rico.
18 U.S.C. §597. Expenditures to influence voting
Whoever makes or offers to make an expenditure to any person, either to vote or withhold his vote, or to vote for or against any candidate; and
Whoever solicits, accepts, or receives any such expenditure in consideration of his vote or the withholding of his vote—Shall be fined under this title or imprisoned not more than one year, or both; and if the violation was willful, shall be fined under this title or imprisoned not more than two years, or both.