Sections 54.9801-1 through 54.9801-6, and 54.9831-1 and this section are applicable for plan years beginning on or after July 1, 2005. Notwithstanding the previous sentence, for short-term, limited-duration insurance sold or issued on or after September 1, 2024, the definition of short-term, limited-duration insurance in § 54.9801-2 applies for coverage periods beginning on or after September 1, 2024. For short-term, limited-duration insurance sold or issued before September 1, 2024 (including any subsequent renewal or extension consistent with applicable law), the definition of short-term, limited-duration insurance in 26 CFR 54.9801-2, revised as of April 1, 2023, continues to apply, except that paragraph (2) of the definition of short-term, limited-duration insurance in § 54.9801-2 applies for coverage periods beginning on or after September 1, 2024.