This paper aims at examining the impact that Computer-Aided Translation (CAT) tools have on the degree of accessibility achieved during the localisation process. More specifically, we report on the findings from a two-stage study consisting of 1) a descriptive analysis of two CAT tools, i.e. SDL Trados Studio 2017 and MemoQ v8.7, and 2) a user evaluation carried out by 10 participants to determine whether these tools can support and transfer accessibility features embedded in HTML5 files. Results of the first stage show that the two CAT tools studied do not offer sufficient features and functionalities to transfer all items correctly and, consequently, they can have an effect on the final level of accessibility conformance. In addition, conclusions drawn from the user evaluation highlighted the importance of the localiser's role in dealing with this type of elements, as participants with more knowledge of the subject were able to produce a more accessible target file.