Estimated payments are due on the 15th day of the fourth, sixth, and ninth month of the current tax year, and the 15th day of the first month of the next tax year. For example, a calendar year taxpayer’s estimated payment are due on April 15, June 15, and September 15 of the current year, and January 15 of the next year.
The penalty rate for delinquent and deficient estimated tax payments is 2% per month, up to a maximum of 24%, plus interest at the current rate per year.
Reference: Tenn. Code Ann. §§ 67-4-2015; 67-1-801; 67-1-803(d).