CO2 Regulatory Certainty Act This bill amends the Internal Revenue Code to revise requirements for the secure geological storage of carbon oxide. The bill requires the Internal Revenue Service (IRS), in consultation with other federal agencies, including the Environmental Protection Agency (EPA), to prescribe regulations for determining adequate security measures for the geological storage of carbon oxide so that it does not escape into the atmosphere. The IRS regulations must consider the carbon oxide to be disposed of in secure geological storage if it is stored in compliance with specified rules promulgated by the EPA under the Clean Air Act and the Safe Drinking Water Act for the geologic sequestration of carbon oxide. The bill also revises the definition of "qualified enhanced oil or natural gas recovery project" to exclude a requirement for the first injection of liquids, gases, or other matter to commence after December 31, 1990.