Notice 2021-37 sets forth updates on the corporate bond monthly yield curve, the corresponding spot segment rates for June 2021 used under § 417(e)(3)(D), the 24-month average segment rates applicable for May 2021, and the 30-year Treasury rates, as reflected by the application of § 430(h)(2)(C)(iv). 

Notice 2021-37 will be in IRB:  2021-26, dated June 28, 2021.