Can You Challenge a Prenuptial Agreement? A Guide to Overturning Prenups in England in 2026

Can You Challenge a Prenuptial Agreement? A Guide to Overturning Prenups in England

Prenuptial agreements are not automatically binding in England and Wales. Since the Supreme Court’s decision in Radmacher v Granatino [2010], courts have been required to give effect to a prenuptial agreement that was freely entered into by both parties with full financial disclosure and independent legal advice, provided it is not unfair to hold them to it. That final qualification matters. The court is not automatically bound by what the parties agreed to before the wedding. It retains the power to depart from the terms where fairness requires it.

For some clients, that power is essential. Whether a prenuptial agreement was signed under pressure, whether the agreement did not reflect one party’s financial reality at the time of signing, or whether one party’s needs are now simply not met by the provision in the agreement, there are established routes to challenge an agreement and to seek a substantially higher award from the court.

This guide explains when and how prenuptial agreements can be overturned, what the court looks for, and what a challenge can achieve.

Are Prenuptial Agreements Legally Binding in England and Wales?

Prenuptial agreements are not automatically legally binding in England and Wales. Unlike in many other jurisdictions, English courts do not treat a prenuptial agreement as an enforceable contract in the strict sense. Instead, following the Supreme Court’s landmark decision in Radmacher v Granatino [2010], courts are required to give significant weight to a prenuptial agreement where it was freely entered into by both parties with a full appreciation of its implications, provided that it would not be unfair to hold them to it.

That qualification is that it must not be unfair to hold the parties to the agreement, and this is key. The court retains an overriding duty to achieve a fair outcome in financial remedy proceedings. It will always have the power to depart from a prenuptial agreement where enforcing it would produce an unjust result. A prenuptial agreement that meets all the procedural requirements can still be set aside if the circumstances at the time of divorce are materially different from those at the time it was signed, or if strict adherence would leave one party in genuine financial need.

The Law Commission has recommended that qualifying nuptial agreements be made formally enforceable by statute, subject to prescribed procedural safeguards. That legislation has not yet been passed. Until it is, the Radmacher framework applies, and the grounds for challenging a prenuptial agreement remain available.

The Legal Framework: Radmacher and the Limits of Party Autonomy

The Supreme Court in Radmacher established that the weight given to a prenuptial agreement depends on whether it was freely entered into by both parties with a full appreciation of its implications. Courts are required to give effect to such an agreement unless it would be unfair to do so.

That is not the same as making prenuptial agreements enforceable as a matter of contract. The court’s overriding duty in financial remedy proceedings is to achieve a fair outcome. Party autonomy is a relevant factor in determining what is fair, but it is not the only one. Where the court concludes that strict adherence to the agreement would produce an unfair result, it will depart from the terms.

The Law Commission has recommended introducing a statutory category of qualifying nuptial agreements, which would be formally binding if certain procedural safeguards are met. That recommendation was made 14 years ago. A more recent scoping review in 2023 and 2024 has recommended reform of the law on financial remedies, but no firm response on timing or framework has yet been formulated. In the meantime, the Radmacher framework applies, and the grounds for challenge remain available.

Grounds for Challenging a Prenuptial Agreement

1. Needs

A court will not enforce a prenuptial agreement that leaves one party in real financial need. The needs of the parties, and particularly those of any children, constitute a threshold that the agreement cannot override. In KA v MA, the court departed from the prenuptial agreement because adhering to it would not have met the wife’s needs. She was awarded a further £2.65 million above the agreed terms on that basis.

Needs can change significantly over the course of a marriage. A couple who married and had financial positions which were broadly equal may, twenty years later, find themselves in very different circumstances, particularly where one party has reduced – or even extinguished – their income to care for children. An agreement that was fair in its original context may no longer be so.

2. Absence of Independent Legal Advice

Both parties should have received independent legal advice before signing the agreement. If one party was unrepresented or did not fully understand the nature and effect of the pre-nuptial agreement, the agreement is vulnerable to challenge. Courts treat the absence of proper legal advice as a significant indicator that the party did not enter the agreement with a full appreciation of its implications.

3. Duress, Undue Pressure, or Misrepresentation

An agreement signed under duress or undue pressure may not be upheld. Pressure can take many forms. Being presented with an agreement shortly before the wedding date, being forced to sign it, or signing while emotionally distressed are all relevant factors.

4. Inadequate Financial Disclosure

Each party must have provided a complete and accurate picture of their financial position at the time of signing. If one party concealed assets, undervalued a business, or otherwise gave incomplete disclosure, the other party cannot be said to have entered the agreement with a full understanding of what they were agreeing to. Non-disclosure, along with needs, is one of the most frequently argued grounds in prenuptial agreement challenges.

5. Changed Circumstances

Courts will also look at whether circumstances have changed in a way that makes it unfair to hold the parties to the original terms. The arrival of children, a significant change in one party’s earning capacity, the receipt of a large inheritance, or a substantial increase in the value of one party’s assets can all shift the balance. An agreement designed for a short marriage with no children may be wholly unsuitable for a twenty-year marriage with three children and a very different financial picture.

6. Failure to Meet the Required Formalities

Agreements signed too close to the wedding date, or where the formalities of execution were not properly followed, are more susceptible to challenge. Courts expect agreements to be finalised well in advance of the ceremony. An agreement signed within a few weeks of the wedding attracts greater scrutiny.

In practice, the most frequent ground for challenging a pre-nuptial agreement is a failure to meet needs. It is often extremely difficult – if not impossible – to predict a family’s financial trajectory with any accuracy, particularly for a young couple at the beginning of their marriage. One often finds that the more rigid and prescriptive the agreement is, the more open it is to challenge. For example, an agreement which provides the weaker party should receive a prescribed lump sum in settlement of their financial claims might well look extremely generous at the outset of a marriage, when the family is in growth-mode; however decades down the line, if one party has earned a significant amount of money, that lump sum may start to look mean, opening the agreement up to challenge.

KA v MA: What Happens When the Court Departs From a Prenup

KA v MA is a significant reported case in which the court exercised its power to depart from the terms of a prenuptial agreement on the grounds of need. The wife was awarded a further £2.35 million above what the agreement provided. The case illustrates that a prenuptial agreement, even one properly drafted and signed, does not determine the outcome of financial remedy proceedings where adherence to it would be unfair.

The judgment underlines two key points. First, that needs to represent a floor that a prenuptial agreement cannot undercut. Second, the circumstances prevailing at the date of the marriage may look very different from those that exist at the date of separation, and the court will take account of that change.

This case also illustrates the importance of keeping the provision in pre-nuptial agreements flexible. In this case, the spousal maintenance provision of £24,000 per annum was found to be seriously lacking in the context of a couple who spent an estimated £1 million per annum to meet their needs. Whilst the court’s view was that the agreement should not be upheld, its existence nevertheless represented a significant factor that reduced the capital awarded to the wife (for housing and a capitalised sum in respect of her income claims). The judge acknowledged that in the absence of a pre-nuptial agreement, the wife would have been awarded significantly more. In this way, there was some acknowledgement and recognition of the parties’ autonomy to enter into a pre-nuptial agreement, whilst the court ensured that this did not mean the parties’ needs were overlooked.

What Happens in Practice: Challenging a Prenup in Financial Remedy Proceedings

A challenge to a prenuptial agreement occurs in financial remedy proceedings. The agreement does not disappear from the proceedings; it is placed before the court as a relevant – and indeed very significant – factor, and the parties will argue the weight to be attributed to it.

Courts look at the full picture when determining the extent to which the agreement should be upheld or departed from. Of relevance will be: the history of the marriage, the financial positions of both parties, the needs of any children, and the extent to which the agreement was properly entered into. The court has ample discretion to award a result that is fair, regardless of what the agreement says.

The most effective challenges combine procedural arguments with a strong case on needs, lack of disclosure or changed circumstances. Where a court can be shown both that the process was flawed as well as the provision being seen to be unfair to one of the parties, the prospects of departure are considerably stronger.

International and Cross-Border Prenuptial Agreements

Where a prenuptial agreement was signed in another jurisdiction, and/or where one or both parties have significant connections to other jurisdictions, additional complexity arises. An agreement that is formally binding in one country may carry a different weight in English proceedings. English courts apply their own framework when deciding whether to uphold an overseas prenuptial agreement, and the Radmacher principles apply regardless of where the agreement was made.

Cross-border prenuptial agreements also raise questions about which law governs the agreement, how assets across multiple jurisdictions are to be treated, and whether the formalities required in the relevant foreign jurisdiction were observed at the time of signing. These are specialist issues that require advice from a family lawyer experienced in international financial remedy proceedings.

If a couple with a pre-nuptial agreement entered into overseas moves to England, they should immediately seek advice from an English family lawyer on the necessary steps to ensure it is upheld in this jurisdiction. Often, it is advisable to enter into a fresh agreement (post-nuptial agreement), which may involve renegotiating the terms completely. Alternatively, that agreement may simply reconfirm the parties’ continued intent to be bound by the original pre-nuptial agreement. Failure to do so may have fatal consequences for the party seeking to uphold the agreement. For example, parties who have entered into a straightforward “séparation de biens” marriage contract in France, which will not have involved independent legal advice and may not have entailed thorough financial disclosure, will not automatically be upheld in England, but, provided the English court sees the outcome as fair, may carry significant weight.

Special mention should be given to parties who have entered into an Islamic marriage in a country in which such marriages are considered to be valid. Often, the Nikkah (marriage contract) will stipulate what the wife may receive in monetary terms following a divorce. However, an English court looking at such a divorce would remain bound to consider the Radmacher principles, most notably fairness, in assessing what weight (if any) ought to be given to such terms.

Postnuptial Agreements: Can These Be Challenged?

A postnuptial agreement is entered into after marriage and serves the same purpose as a prenuptial agreement: to set out how assets will be divided if the marriage breaks down. Courts apply the same Radmacher framework when deciding whether to uphold a postnuptial agreement, and the grounds for challenging one are identical to those that apply to prenuptial agreements.

Postnuptial agreements are frequently used where couples did not have a prenuptial agreement before the wedding, or where circumstances have changed significantly during the marriage. Common triggers include the receipt of a substantial inheritance, the sale of a business, or a significant shift in the financial balance between the parties. They can also be used to update the terms of an existing prenuptial agreement that no longer reflects the parties’ current position.

As with prenuptial agreements, a postnuptial agreement can be challenged where it fails to meet the financial needs of one party, where circumstances at the time of divorce differ materially from those at signing, or where the procedural requirements of free will, full disclosure, and independent legal advice were not met. Courts have shown a willingness to depart from postnuptial agreements on needs grounds in precisely the same way they depart from prenuptial agreements.