The article aims to present the implementation of the national census carried out in Poland in 2021 as a process, with particular attention devoted to the challenges that national censuses pose for official statistics. The paper also focuses on how the organiser of the census – Statistics Poland – addressed the problems reported during the survey. The significance of the census results as a source of information was also discussed. The research was based on a case study, which allowed an in-depth analysis of the census process. The results of the analysis show that the problems which occurred in the National Population and Housing Census 2021 were similar to those identified in the previous editions of the survey, such as questions relating to sensitive information and the potential ways in which the answers to this type of queries could be further processed. What is more, maintaining the digital (electronic) form of the census (the paper forms were abandoned in favour of the digital form in 2011) and the introduction of the Internet-based self-enumeration as the primary form of the survey, applicable to all its participants, created additional challenges, related to some respondents’ lack of digital skills or limited access to the Internet. Statistics Poland offered a variety of forms of contact with the society and addressed Internet users’ questions on an ongoing basis, mainly through information campaigns, which included using social media, and by directly responding to Facebook users’ comments. The conducted analysis provides a useful insight as to how reliable data could be collected in a census, particularly with the use of the Internet.