Notice 2021-08 provides a waiver of the addition to tax under § 6654 for underpayment of estimated income tax by individual taxpayers, where the underpayment is attributable to the amendment to § 461(l)(1)(B) made by the CARES Act.  The relief, which is not automatic, applies only for the purpose of calculating installments of estimated income tax of an affected individual taxpayer that were due on or before July 15, 2020, with respect to the taxable year that began during 2019. 

Notice 2021-08 will be in IRB:  2021-6, dated 02/08/2021.