We investigate experimentally the effects of the opportunity to pre‐plan one's action on dynamic (im)moral decision makings in two stages. In the experiment we either provided the subjects at the outset with the information that they might be able to tell lies to improve their payoff repeatedly (hence they could pre‐plan accordingly), or provided such information at the beginning of each stage (and hence they could not pre‐plan). Furthermore, we controlled whether they had the incentive to resort to telling a lie in the first stage or not. Our two main findings are: (i) when subjects were not informed about the second opportunity to lie at the outset, those who had an opportunity to lie in the first stage lied more often in the second stage compared to those who did not have such an opportunity; and (ii) pre‐planning induced subjects to lie more often in the first stage. We conjecture that pre‐planning invited a compensatory, instead of consistent, action, and thus induced more dishonest responses in the beginning and fewer later. We also discuss the extent of ‘partial lying’, i.e., lying in only one stage, across the treatments and its effect on the overall rate of lying.