Sustainable Skies Act This bill allows a business-related tax credit through 2031 for each gallon of sustainable aviation fuel used by a taxpayer in the production of a qualified mixture (i.e., a mixture of sustainable aviation fuel and kerosene that is sold for use in certain U.S. aircraft). The bill generally defines sustainable aviation fuel as liquid fuel that consists of synthesized hydrocarbons, meets certain recognized international standards, is derived from biomass, waste streams, renewable energy sources, or gaseous carbon oxides, is not derived from palm fatty acid distillates, and achieves at least a 50% life cycle greenhouse gas emissions reduction in comparison with petroleum-based jet fuel. To be eligible for such credit, a taxpayer must meet certification requirements showing that the sustainable aviation fuel conforms with one of the life cycle greenhouse gas emissions reduction tests set forth in this bill.