The IRS interest rates on overpayments and underpayments for the fourth quarter of 2022 are one percentage point higher than in the third quarter (Rev. Rul. 2022-15). This is the third interest rate increase this year. The rates beginning October 1, 2022, are:
Generally, an unmarried person who maintains a household for dependents and is allowed to compute his or her tax based on head of household rates, which are more favorable than single person rates.