Makes three changes to tax rules: it treats the timestamp of an electronic submission or payment to the IRS as the official date of delivery even if the IRS processes it later; it gives the IRS authority to treat some late S‑corporation elections or revocations as timely and updates related coordination rules; and it delays two individual estimated‑tax deadlines (June 15 -> July 15 and Sept 15 -> Oct 15). Most changes take effect for documents or tax years after December 31, 2025, and the IRS must issue guidance by the end of 2025.