Depreciation is an income tax deduction that allows a taxpayer to recover the cost of property or assets placed in service. Straight line depreciation is the most frequently used method of depreciating new equipment for financial statements. Accelerated cost recovery systems include the methods like declining balance depreciation and sum-of-years digits depreciation. Incomplete information about the future values of the parameters in an after-tax rate of return analysis causes us to use the fuzzy set theory. This chapter includes the fuzzy after-tax cash flow analyses in case of fuzzy cash flows, fuzzy depreciation, fuzzy tax rate, and fuzzy minimum attractive rate of return with numerical examples. © 2008 Springer-Verlag Berlin Heidelberg.