We analyze the optimal dividend payment problem in the dual model under constant transaction costs. We show, for a general spectrally positive L{e}vy process, an optimal strategy is given by a $(c_1,c_2)$-policy that brings the surplus process down t
o $c_1$ whenever it reaches or exceeds $c_2$ for some $0 leq c_1 < c_2$. The value function is succinctly expressed in terms of the scale function. A series of numerical examples are provided to confirm the analytical results and to demonstrate the convergence to the no-transaction cost case, which was recently solved by Bayraktar et al. (2013).
