Objectives:
The subject of the study is to examine the functioning of the internet sales systems of Polish regional railway carriers with regard to the obligation to inform about the lowest available fare under Regulation (EU) 2021/782 of the European Parliament and of the Council. Due to the complexity of the fare structure used by carriers, there may be cases in which the cheapest fare on a given route may require making a 'non-standard' purchase: purchasing more than one ticket or a ticket for a route different from the one that will actually be travelled.

Material and methods:
he fare structure of carriers and the operation of sales systems to support the abovementioned "non-standard" ticket purchases were examined.

Results:
The results of the research showed that the sales systems of most carriers do not support the abovementioned 'non-standard' purchases through an automatically generated offer. Nevertheless, such a purchase is technically possible, but only through a user's own request.

Conclusions:
As conclusions from the study, de lege ferenda postulates were formulated regarding the clarification of the very provision on the obligation to inform about the lowest cost contained in the Regulation, as well as the rules for the operation of sales systems and the creation of transport tariffs.