LA HB633

Extends the deadline for calculating the underpayment period for estimated income taxes from the 15th day of the fourth month to the 15th day of the fifth month following the close of the taxable year, for both individuals and corporations

Changes the deadline for corporations to file applications for adjustment of overpayment of estimated income tax from the 15th day of the fourth month to the 15th day of the fifth month after the taxable year closes

Repeals the penalty exemption for individual taxpayers who calculate their estimated tax based on 90% of annualized taxable income

Eliminates the annualized basis computation method for corporations to qualify for the underpayment penalty exemption, while retaining the 80% of current year tax exception

Applies to income tax periods beginning on or after January 1, 2026, and takes effect upon the governor's signature