California's Political Reform Act requires candidates and campaign committees to file reports disclosing their receipts and expenditures. A special requirement of the law is that "late contributions" and "late independent expenditures" must be disclosed on reports filed within 24 hours of the activity, and these reports must be filed by fax, telegram, guaranteed overnight mail, or personal delivery.

A "late contribution" is a contribution of $1,000 or more (in the aggregate) made to, or received by, a candidate or ballot measure committee during the 16 days immediately preceding the election. A "late independent expenditure" is an independent expenditure (i.e., an expenditure not made to, or at the behest of, a candidate or ballot measure committee) of $1,000 or more (in the aggregate) to support or oppose a candidate or ballot measure during the 16 days immediately preceding the election.