The Internal Revenue Service assessed a penalty against Boechler, a North Dakota law firm, and sustained a levy after a collection due-process hearing. Boechler filed its petition for review more than thirty days after the agency’s determination, and the Court of Appeals held that the filing deadline was jurisdictional and could not be equitably tolled. The Supreme Court reversed. It held that the thirty-day deadline is an ordinary claims-processing rule rather than a limitation on federal subject-matter jurisdiction. The statutory text did not clearly make the deadline jurisdictional, and equitable tolling may therefore be available when the facts justify it. The Court did not decide whether Boechler was entitled to tolling on the existing record. It remanded for that determination.