Finite Impulse Response (FIR) filters are widely applied in multistandard wireless communications. The two key requirements of FIR filters are reconfigurability and low complexity. In this paper, two reconfigurable FIR filter architectures are proposed, namely Constant Shift Method (CSM) and Programmable Shift Method (PSM). The complexity of linear phase FIR filters is dominated by the number of adders (subtractors) in the coefficient multiplier. The Common Subexpression Elimination (CSE) algorithm reduces number of adders in the multipliers and dynamically reconfigurable filters can be efficiently implemented.