The IRS has announced that the interest rates applicable to overpayments and underpayments of federal taxes for the fourth quarter of 2019 are the same as for the third quarter of the year (Rev. Rul. 2019-21). The rates are:
Net income after claiming all deductions from gross income and adjusted gross income, such as IRA deductions, itemized deductions, or the standard deduction, and personal exemptions.