The penalty relief applies to any installment of estimated tax for 2024 tax years (e.g., installments due September 16, 2024, and December 15, 2024). In Notice 2024-66, the IRS has waived the penalty under IRC Section 6655 for a corporation's failure to pay estimated tax installments attributable to its alternative minimum tax (CAMT) liability under IRC Section 55 for any tax year that begins after December 31, 2023, and before January 1, 2025.At the same time, the IRS released the long-awaited CAMT proposed regulations (REG-112129-23), which propose rules regarding the application of the 15% CAMT on the adjusted financial statement income...