710:50-13-3 Who must make payments of estimated tax; due dates

(a) Payment of estimated income tax must be made by the following: (1) A single individual whose tax liability for the year is estimated to be $500.00 or more in excess of taxes withheld from wages. (2) Married individuals whose combined tax liability for the year is estimated to be $500.00 or more in excess of taxes withheld from wages. (3) A corporation or trust whose tax liability for the year is estimated to be $500.00 or more. (b) Initial payments of estimated tax should be made by: (1) Calendar-year taxpayers, no later than April 15th. (2) Fiscal-year taxpayers, by the fifteenth day of the fourth month following the beginning of the taxable year. [ See: 68 O.S. § 2385.7]