Abstract One of the important goals of Iran’s health transformation programme (HTP) is to improve financial protection for households against health expenditure. This study aimed to investigate the occurrence, intensity and inequality in distribution of catastrophic health expenditure (CHE) using the WHO and the World Bank (WB) methodologies with different thresholds in the years before and after HTP. We used data from seven annual national repeated cross-sectional surveys on households’ income and expenditures from 2011 to 2017. The intensity to CHE was calculated using overshoot and mean positive overshoot (MPO) indices. Finally, the inequality in distribution of exposure to CHE was calculated using the concentration index (CI), and the dominance test of concentration curves was used to inference about the significant changes in inequality of the years before and after HTP. The exposure rate to CHE in the total population and at 40% threshold of the WHO methodology changed from 1.99% in 2011 to 3.46% in 2017. Additionally, at 20% threshold of the WB methodology, it was changed from 5.14% to 8.68%. Overshoot and MPO indices increased on average based on two methodologies in urban and rural areas during seven years. The CIs for all the years show a negative value in both methodologies, indicating that CHE occurrence is higher among the poor households. In 2017, at 40% threshold of the WHO, the numerical values of the CIs were −0.15 and −0.14 in urban and rural populations, respectively. These values were −0.07 and −0.05 for the 20% threshold of WB, respectively. Results of dominance test showed no significant change in inequality for the years after than before HTP with two exceptions for total and rural populations based on the WB methodology. Generally, HTP had no considerable success in financial protection, requiring a review in actions to support pro-poor adaptation strategies.