Notice 2021-55 explains the circumstances under which the four-year replacement period under section 1033(e)(2) is extended for livestock sold on account of drought. The Appendix to this notice contains a list of counties that experienced exceptional, extreme, or severe drought conditions during the 12-month period ending August 31, 2021. Taxpayers may use this list to determine if an extension is available. 

Notice 2021-55 will be in IRB: 2021-41, dated October 12, 2021.