In this paper, a method is proposed for designing the command feedforward controller for zero phase error tracking control of systems having unacceptable zeros. The unacceptable zeros include both non-minimum phase zeros and lightly damped zeros. In the proposed approach, a digital preview filter along with the acceptable part of the system’s inverse model is designed to form the command feedforward controller. Using preview information of the input trajectory, the designed tracking controller guarantees zero phase error and high precision tracking performance. In the proposed design, the best tracking performance can be achieved by minimizing a weighted penalty function, which controls the gain error between the desired output and the actual output. Two design cases were examined. The first is the design based on a uniform weighting function. In this study, the optimal solution of the design can be analytically obtained and three prior approaches were shown to be the special cases of the proposed solution. The second case is the design based on input trajectory. It was shown that in the trajectory-based design, the proposed penalty function in the frequency domain is, in fact, the total squared tracking errors in the time domain. Therefore, the proposed digital preview filter based on input trajectory is the optimal solution in achieving the best tracking performance.