The EU will publish all documents, related to negotiations with the UK, which are shared with EU member states.
The EU Commission tweeted on 22 May 2017:
We want full transparency. #Article50 negotiating documents will be released to the public & will be published here.
The Commission, as European Union negotiator, will ensure a maximum level of transparency during the whole negotiating process.
Commission negotiating documents which are shared with EU Member States, the European Council, the European Parliament, the Council, national parliaments, and the United Kingdom will be released to the public.
Documents wil be provided at
Some of the initial documents available are:
Recommendation for a Council Decision authorising the Commission to open negotiations with the UK setting out arrangements for its withdrawal from the EU
Annex to the Commission recommendation on negotiations with the UK
European Council (Art. 50) guidelines for Brexit negotiations
Directives for the negotiation of an agreement with the United Kingdom of Great Britain and Northern Ireland setting out the arrangements for its withdrawal from the European Union
European Commission receives mandate to begin negotiations with the UK
Statement by Michel Barnier at the press conference following the General Affairs Council (Art. 50)