Recently, the interest in induced polarization (IP) phenomenon in airborne time-domain electromagnetic (ATEM) data has been significantly increased. 2D induced polarization greatly affects the ATEM data and masks underlying geological structures. In order to simulate rigorous 2D airborne IP data, a 2.5D modeling algorithm has been developed using the Cole-Cole model and the finite-element method. We verify our algorithm by comparison with the 1D solution of the AarhusInv code. 2D IP effects in the ATEM data are related to the four Cole-Cole parameters, the horizontal length of the 2D target and the distance between the receiver and the target. Compared to the 1D IP responses, the 2D responses are different especially at the stations near the edge of the 2D target. The general shape of the 2D target except for the edge can be recovered by the 1D Laterally Constrained Inversion (LCI) of AarhusInv.