The depreciation tax deduction is calculated according to the standard Modified Accelerated Cost Recovery System (MACRS) tables. A geothermal power plant is commonly assumed to be deductible using a '5-year' recovery period. The depreciation tax deduction, , is the product of the MACRS coefficient, , given in Table and the total capital cost of the geothermal plant (Equation S18). The Income Tax for any year, , is the product of taxable income, , and the tax rate, , given in Equation S19.