S. 5441, the Taxpayer Assistance and Service Act, is a comprehensive overhaul of IRS operations aimed at improving taxpayer service, strengthening oversight of tax preparers, and expanding taxpayer rights in disputes with the agency. It requires the IRS to modernize by accepting all returns electronically, digitizing paper documents, creating online taxpayer accounts, and meeting new deadlines for processing refund claims and information returns, with most changes phased in over 6 to 24 months after enactment. The bill also imposes tougher penalties and stricter licensing standards on tax return preparers—including new criminal penalties for fraudulent preparer ID numbers and unauthorized disclosure of taxpayer data—while expanding the Tax Court's jurisdiction to hear larger refund suits, judicial conflict-of-interest rules, and broader appeal rights through the IRS Independent Office of Appeals. Special protections are created for Americans wrongfully detained or held hostage abroad, pausing tax deadlines and penalties during their captivity, and farmers and fishermen get a simplified estimated tax deadline aligned with the standard April 15 date. Overall, the bill affects everyday taxpayers, tax professionals, IRS employees, and Americans abroad, with funding tied to expanded IRS enforcement and technology upgrades and most provisions taking effect between 180 days and two years after the bill becomes law.