The Board is responsible for adjusting and equalizing the valuation of real and personal property of the several counties of Oklahoma.

Board is also responsible for providing an estimate of all revenue that will be available for appropriation by the Oklahoma Legislature for the coming fiscal year.

As established by Article 10 of the Oklahoma Constitution, the Board was composed of seven elected officials.

As of 2022, the current membership of the Board is as follows: On December 1 of each year, or the first working day thereafter, the Board must equalize the taxable real and personal property value of the several counties for the purpose of tax assessment by the county assessors.

The Board is responsible for determine the assessment ratio for all air carrier, railroad, and public service corporation property in the state.