This legislation, titled the "Electronic Filing and Payment Fairness Act," amends the Internal Revenue Code of 1986 to apply the established mailbox rule to electronically submitted documents and payments made to the Internal Revenue Service. Specifically, it mandates that if any return, claim, statement, document, or payment is sent electronically, the date it is sent by the person will be deemed the date of delivery or payment. This provision applies regardless of the actual date the IRS receives or reviews the submission, providing clarity and fairness for electronic transactions. The Secretary of the Treasury is required to issue necessary regulations or guidance by December 31, 2025, to carry out these purposes, with the amendments taking effect for any document or payment sent after December 31, 2025.