Prenups, petnups and postnups – What do you need to know?

When we think of entering a marriage or cohabiting, the legal aspects are often the last thing on our minds.

The growing popularity of prenuptial and postnuptial agreements, however, along with petnups, highlights the practicality of planning for various eventualities.

Prenuptial agreements (Prenups)

A prenuptial agreement, often known as a prenup, is a legal document entered into before marriage or civil partnership. It details the division of assets, liabilities and financial responsibilities should the relationship end in divorce or dissolution.

Are prenups legally binding?

In England and Wales, there is no legislation dealing with prenuptial agreements and thus their recognition has developed in case law.

The courts are more likely to uphold a prenup, provided it is deemed fair, and both parties fully understood the implications when entering into the agreement.

The courts also require the following criteria to be met:

  • Full disclosure – Both parties must have been honest and transparent about their financial circumstances.
  • No undue pressure – Neither party should have been pressured or coerced into signing the agreement.
  • Legal advice – Both parties must have independent legal advice to understand the terms and implications.
  • Signature – Both parties should sign off the agreement at least 28 days before the wedding or civil partnership.


A petnup is a document much like a prenuptial agreement, however, it specifies the living conditions of pets should a divorce or dissolution occur.

While pets are often considered part of the family, pets are categorised as chattel, meaning they are classified as an item of personal property. In a technical sense, the individual who purchased the animal and to whom it is registered will retain ownership.

Currently, the only method to resolve a disagreement concerning arrangements for pets and their living circumstances is through filing an application in Court.

Petnups are not fundamentally legally binding documents. Nevertheless, if it is meticulously planned and encompasses all the vital aspects of the pets’ living and care provisions, the Court will consider it when making a decision.

Key points to consider when drafting a petnup

  • Responsibility – The agreement should define who will take care of the pet, including financial responsibilities for upkeep.
  • Welfare – Considering the welfare of the pet is paramount. The agreement should be in line with the Animal Welfare Act 2006.
  • Enforcement – Though not always legally binding, a petnup can still hold significant weight in a legal dispute.

Postnuptial agreements (Postnups)

Postnuptial agreements are legal documents created after marriage or civil partnership, detailing financial and property rights, and how they will be dealt with if the relationship breaks down.

Again, like prenups and petnups, while not strictly legally binding in court, they are given significant weight if executed voluntarily and fairly, with full financial disclosure from both parties, each party having independent legal advice.

Postnups offer clarity and certainty, providing a blueprint for asset division if the relationship ends.

They often protect significant assets brought into or acquired during the relationship, such as inheritance and can help minimise conflict over financial matters in case of divorce.

A postnuptial agreement can be tailored to a couple’s unique situation, making it a flexible tool that evolves with the relationship.

Seeking professional legal advice is strongly recommended to ensure compliance with the law and alignment with both parties’ interests.

Prenups, petnups and postnups represent a modern approach to managing relationships and assets in today’s ever-changing landscape. While not always legally binding, they can play a significant role in providing clarity and protecting individual interests.

For help and advice with family and relationship matters, please get in touch with Alison Green, Head of our Family and Relationship Team at Mackrell.Solicitors on +44 (0) 20 7240 0521 or at

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Alison Green
Alison has more than 25 years’ experience assisting clients with Family and Relationship matters. Her expertise covers matrimonial work, including divorce and the associated financial and children issues; pre and post-nuptial agreements; co-habitation disputes; civil partnership agreements and the breakdown of civil partnerships.