Purpose: The paper presents early evidence from GPW Main Market-listed companies on the implementation of the InlineXBRL format and the ESEF mandate. Methodology/approach: Semi-structured, detailed interviews with GPW issuers are the basic research method used. Representatives of ten listed companies were interviewed. Results: The study indicates that InlineXBRL implementation is a challenge that involves significant human, time and financial resources. Moreover, it reveals that the only reason for XBRL implementation among Polish issuers is compliance with statutory requirements rather than other XBRL benefits. Ninety percent of respondents implemented the bolt-on approach, which enables fast compliance with statutory requirements; however, it does not support internal reporting and does not facilitate the financial reporting process. The study results are consistent with XBRL implementation evidence from American early adopters and confirm the thesis that an XBRL mandate is the main driver of XBRL dissemination. Limitations: The relatively small research group (10 companies). Originality/value: This study is the first in this field conducted in Poland, and this paper claims to be the first Polish one to name, structure and describe InlineXBRL implementa-tion options.