This paper presents a novel methodology for estimating impacts on domestic supply of oil and natural gas from changes in the tax treatment of oil and gas production. Using this approach along with simple market models for oil and natural gas, it finds that removing the major tax preferences for the oil and gas industry would have modest impacts on global oil production, consumption or prices. Domestic oil and gas production is estimated to decline by 4 to 5 percent over the long run. Global oil prices would rise by less than one percent. Domestic natural gas prices are estimated to rise by 7 to 10 percent.