This study investigated the potential of ex-post fare policy evaluation utilising smartcard data. It looked into how to identify and measure the actual outcomes of a policy, define the degree of its success, and even find some unexpected side-effects of high importance. The study is based on a case of the public transport fare policy introduced by the regional administration of Stockholm County in January, 2017. The policy focused on changing the fare structure basis, in particular switching from a zonal to a flat-fare scheme. The goal of the study is to determine how the policy affected the traveling behavior of different public transport user groups and what equity implications it brought. Altogether, these insights could be transformed into lessons for designing a more advanced evaluation approach and future policy-making.