Okla. Stat. tit. 68, § 68-2385.9

A. The required annual payment of estimated tax shall be paid

in four equal installments as follows:

1. In the case of a taxpayer on a calendar year basis, the

first installment shall be paid on April 15 of the taxable year, the

second and third on June 15 and September 15, respectively, of the

Oklahoma Statutes - Title 68. Revenue and Taxation Page 1079

taxable year and the fourth on January 15 of the succeeding taxable

year. However, if taxpayer files return and pays tax due on or

before January 31, the payment of the installment due January 15 is

waived; and

2. In the application of this section to the case of a taxable

year beginning on any date other than January 1, there shall be

substituted, for the months specified in this section, the months

which correspond thereto.

B. As used in this section, the “required annual payment” shall

mean the lesser of:

1. Seventy percent (70%) of the tax shown on the return for the

taxable year; or

2. One hundred percent (100%) of the tax shown on the return

for the preceding taxable year of twelve (12) months.

C. For purposes of determining the amount of tax due on any of

the respective dates, taxpayers may compute the tax by placing

taxable income on an annualized basis as prescribed by rules

promulgated by the Tax Commission, which shall be in accordance with

the annualization provisions of the Internal Revenue Code. For

corporate taxpayers, the annualization provisions found in Section

6655(e)(2)(c) and 6655(e)(3) of the Internal Revenue Code may not be

used. The provisions allowed in this section for computing

estimated taxes on an annualized basis shall only be permitted for a

taxable year of twelve (12) months.