Is Turkey joining the EU? That was a claim made back in 2016, in one of nearly 1,600 pro-Brexit adverts run by the official Brexit campaign, "Vote Leave" and two associated campaigns, "BeLeave" and "DUP Vote to Leave". At the time the advert was produced, Turkey was involved in accession negotiations. This means it had applied to be a member and was negotiating with the EU - but the process is not a guarantee of membership.