In a written statement to Parliament, the Secretary for Exiting the European Union David Davis said:

The UK will exit the EU on 29 March 2019. We are currently negotiating the terms of our withdrawal (and hope shortly to move on to the terms of our future relationship). This note sets out the role of Parliament in approving the resulting agreements and how they will be brought into force.

There will be at least two agreements.

A Withdrawal Agreement will be negotiated under Article 50 of the Treaty on European Union (TEU) whilst the UK is a member of the EU. It will set out the terms of the UK’s withdrawal from the EU (including an agreement on citizens’ rights, Northern Ireland and any financial settlement), as well as the details of any implementation period agreed between both sides.

Article 50(2) of the TEU sets out that the Withdrawal Agreement should take account of the terms for the departing Member State’s future relationship with the EU. At the same time as we negotiate the Withdrawal Agreement, we will therefore also negotiate the terms for our future relationship.

However as the Prime Minister made clear in her Florence speech, the European Union considers that it is not “legally able to conclude an agreement with the UK as an external partner while it is itself still part of the European Union”. This is because the EU treaties require that the agreement governing our future relationship can only be legally concluded once the UK is a third country (i.e. once it has left the EU). So the Withdrawal Agreement will be followed shortly after we have left by one or more agreements covering different aspects of the future relationship.

The Withdrawal Agreement will need to be signed by both parties and concluded by the EU and ratified by the UK before it can enter into force. The UK approval and EU approval processes can operate in parallel.

The EU’s Chief Negotiator, Michel Barnier, has said that he wants to have finalised the Withdrawal Agreement by October 2018. In Europe, the agreement will then require the consent of the European Parliament and final sign off by the Council acting by a qualified majority. It will not require separate approval or ratification by the individual Member States.

In the UK, the Government has committed to hold a vote on the final deal in Parliament as soon as possible after the negotiations have concluded. This vote will take the form of a resolution in both Houses of Parliament and will cover both the Withdrawal Agreement and the terms for our future relationship. The Government will not implement any parts of the Withdrawal Agreement – for example by using Clause 9 of the European Union (Withdrawal) bill – until after this vote has taken place.

In addition to this vote, the Constitutional Reform and Governance Act 2010 (CRAG) normally requires the Government to place a copy of any treaty subject to ratification before both Houses of Parliament for a period of at least 21 sitting days, after which the treaty may be ratified unless there is a resolution against this. If the House of Commons resolves against ratification the Government can lay a statement explaining why it considers the treaty should still be ratified and there is then a further 21 sitting days during which the House of Commons may decide whether to resolve again against ratification. The Government is only able to ratify the agreement if the House of Commons does not resolve against the agreement.

If Parliament supports the resolution to proceed with the Withdrawal Agreement and the terms for our future relationship, the Government will bring forward a Withdrawal Agreement & Implementation Bill to give the Withdrawal Agreement domestic legal effect. The Bill will implement the terms of the Withdrawal Agreement in UK law as well as providing a further opportunity for parliamentary scrutiny. This legislation will be introduced before the UK exits the EU and the substantive provisions will only take effect from the moment of exit. Similarly, we expect any steps taken through secondary legislation to implement any part of the Withdrawal Agreement will only be operational from the moment of exit, though preparatory provisions may be necessary in certain cases.

As described above, the agreement governing our future relationship with the EU can only be legally concluded once the UK has left the EU. This may take the form of a single agreement or a number of agreements covering different aspects of the relationship.

Whatever their final form, agreements on the future relationship are likely to require the consent of the European Parliament and conclusion by the Council. If both the EU and Member States are exercising their competences in an agreement, Member States will also need to ratify it.

In the UK, the Government will introduce further legislation where it is needed to implement the terms of the future relationship into UK law, providing yet another opportunity for proper parliamentary scrutiny.

The CRAG process is also likely to apply to agreements on our future relationship, depending on the final form they take.

The full text of the statement may be read here.