The European Union wants Northern Ireland to have a different Brexit deal to the rest of the UK, papers seen by the BBC suggest.
Under the plans, people will be able to work, go to school and receive medical treatment either side of the Irish border.
Details will be published by Europe's chief negotiator Michel Barnier in a position paper later.
He has said "a lot more substantial work" was needed on the border issue.
The legislation will convert all existing EU laws into domestic ones ahead of Brexit - due to take effect at the end of March 2019.
Written in the series of position papers are plans to protect Irish cross-border co-operation in areas like health, education, transport and fishing.
The proposals will also include issues such as data protection, intellectual property and customs arrangements.
Ireland's place in the EU's single market or customs union is also mentioned in the document.
It says nothing can affect the country's membership even though the UK government has already said it would leave the customs union.
But, the EU has also reminded Britain that negotiations can only move on when it rules "sufficient progress" has been made on issues of citizens' rights and the UK's financial obligations.
