Aim: Public aid can be involved even in such peculiar public activity sector as culture and heritage conservation. Hence, the EU projects implemented in this area may be subject to legal restrictions on state aid. In this respect, particular legal doubts concerning state aid arise in the context of “impact on trade” premise. This situation is a consequence of both lack of clear definition thereof and the peculiar nature of culture projects. The present paper is aimed at identifying particular issues that ought to be taken into account when determining the possible impact on trade (recommendations for judicature). These issues aren’t actually defined in law, but only in few judgments and literature. Hence, there is a necessity to make further researches.Design / Research methods: Analysis of legal provisions, judgments and literature.Conclusions / findings: 1) It is practically impossible for relevant legal acts to encompass all possible instances of public aid in culture projects. Undoubtedly, judicature (both, of the ECJ and Polish administrative courts) attempts to fill in this peculiar gap by examining and resolving individual cases. 2) Nonetheless, the judicature is not able to account for all possible situations that can be encountered when implementing projects co-financed by the EU, either3) due to the specific nature of this project category, all the above-mentioned aspects and possible interrelations among them need to be considered in great detail. Therefore, each and every case has to be examined separately and individually 4) each of the elements should be examined in detail at every stage of determining whether public aid is granted in a given case (here: from the perspective of possible impact on trade) – both by beneficiaries of the EU funds as well as by institutions involved in management and control system and by administrative courts 5) in individual situations, the sequence of occurrence and intensity of individual elements may differ, which means that each and every case needs to be examined and resolved separately as regards the possible impact on trade and, consequently, the presence of public aid. Originality / value of the article: Contemplated problems are a subject of few judgments and literature. Value of this article is a scientific deepening of all discussed issues. This one is addressed to beneficiaries of the EU funds as well as to institutions involved in management and control system and administrative courts. Implications of the research: This article will enable beneficiaries and mentioned institutions and courts to interpret occurrence of public aid in above-mentioned projects in the appropriate way.