Cohabitation and post-nuptial agreements and polyamory

Joanne McDonald


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February 21, 2023

Categories Family Law

Today, there is no “one size fits all” for relationships. One relationship which is gaining visibility in the media, is one of polyamory. A polyamorous relationship can be defined as one in which people have multiple relationships with multiple partners, at the same time, with the consent of everyone involved. For example, this can mean three people being in an equal intimate and committed relationship. A YouGov survey in January 2023 found that 9% of people asked said whilst they were not in a polyamorous relationship, they would be open to it.

This type of relationship can give rise to legal considerations both in the event of separation and death.

Under the law of England and Wales, a marriage is only legal between two people. There is far more protection and support in place for married people than for those who choose to live together unmarried, in the event of a separation. There is no automatic right for someone to share in the property or assets held by their partner if they are not married, even if they have lived in their partner’s property for some time.

So what can be done to protect a position if your duet becomes a trio?

If buying a property together, particularly with unequal contributions, it is important you instruct a lawyer to prepare a document called a Declaration of Trust which will set out each person’s interest in the purchased property and how these shares should be realised in the event of a separation. More than two people can be party to this agreement.

It would also be sensible to have a cohabitation agreement, particularly if the property being occupied is not held in the names of all parties living in it. This is a bespoke document setting out the terms of cohabitation, such as – what each person’s contributions will be to the outgoings, whether anyone has any interest in the property resided in, when someone will move out in the event of a separation and how will any joint assets and / or debts be dealt with in the event of a separation.

If a couple is already married and a third person joins their relationship, the married parties could enter a post-nuptial agreement setting out their agreement as to the settlement of financial matters in the event of divorce and agree to make provision for the third party in the relationship. Post-nuptial agreements are not currently binding under the law of England and Wales but if they satisfy the court’s requirements and are assessed as fair in all the circumstances and the terms enable the married parties’ needs to be met, the intention is that the court will view the agreement as having magnetic importance in its determination of the issues.

In the above scenario, the third person cannot be party to a post-nuptial agreement, as they are not party to the marriage. However, all three could enter a separate deed recording their intentions for sharing upon separation with reference to the post-nuptial agreement.

For more information about cohabitation agreements, pre and post-nuptial agreements and family law contact Associate, Joanne McDonald on 01634 828277.


See related blog by Senior Associate, Melanie Christodoulou, about wills and powers of attorney >