Prenuptial and postnuptial agreements in England and Wales

In England and Wales, a prenuptial or postnuptial agreement is not automatically legally binding, unlike in some other countries where such contracts are enforced almost as written. What changed in 2010 is that the courts will now give a properly prepared agreement decisive weight. The leading case, Radmacher v Granatino [2010] UKSC 42, established that a court should hold a couple to an agreement they entered into freely, with a full appreciation of its implications, unless in the circumstances it would be unfair to do so. So while a prenup cannot bind a judge, a well-made one is usually followed.

This guide explains what prenups and postnups are, the crucial difference between "persuasive" and "binding", the conditions that make an agreement stand up, what it can and cannot do, and what it costs. Because an agreement is ultimately tested against what a court would consider a fair split, it helps to understand that benchmark first: our settlement range estimator gives an indicative range based on the factors courts actually weigh, so you can see roughly what "fair" looks like before you agree to depart from it.

What a prenup and a postnup are, and the difference

Both documents do the same job: they set out, in advance, how a couple would divide their money, property, pensions and debts if the marriage or civil partnership were to end. The only difference is timing.

• Prenuptial agreement (prenup): made and signed before the wedding or civil partnership ceremony.
• Postnuptial agreement (postnup): made and signed after the couple are already married or in a civil partnership.

A postnup is often used where there was not enough time to finalise an agreement before the wedding, or where circumstances change during the marriage, such as receiving a large inheritance, selling a business, or one partner giving up work. The two are judged against exactly the same legal test, so nothing in this guide turns on which one you have.

The key legal point: not automatically binding

This is the single most important thing to understand, and it is where England and Wales differs from many other legal systems. Only a court can make a financial order on divorce, under the Matrimonial Causes Act 1973. A private agreement between a couple cannot remove that power. So a nuptial agreement is not a contract that the court must enforce; it is a factor the court takes into account.

Before 2010, the courts treated prenups with real caution. The turning point was the Supreme Court's decision in Radmacher v Granatino, where the majority (by eight to one) held a husband to an agreement that excluded him from his wife's substantial fortune. The court set out the test that still applies today:

• A court should give effect to a nuptial agreement that is freely entered into by each party, with a full appreciation of its implications, unless in the circumstances prevailing it would not be fair to hold the parties to their agreement.

In short, a good agreement is highly persuasive and is usually followed, but the court keeps a safety valve: it will not enforce terms that are unfair, and above all it will not enforce terms that fail to meet a spouse's or a child's genuine needs. The Law Commission proposed going further, recommending in its 2014 report Matrimonial Property, Needs and Agreements the creation of "qualifying nuptial agreements" that would be enforceable as contracts, subject to safeguards. That reform has not been enacted, so the Radmacher approach remains the law.

The Radmacher conditions in detail

Breaking the test down, a court is looking at whether the agreement was entered into freely and knowingly, and whether the result is fair. Four things carry most of the weight.

Freely entered into, with no duress

Nobody should feel pressured or rushed into signing. An agreement produced a few days before the wedding, when one person feels they cannot back out without huge embarrassment and expense, is vulnerable to challenge. Signing well ahead of the ceremony is the clearest way to show the decision was free.

Full appreciation of the implications

Both people must understand what they are agreeing to and what they may be giving up. This is why independent legal advice and honest disclosure matter so much: without them, a court can conclude that one person did not really appreciate the implications, which undermines the agreement.

Full financial disclosure

Each person should set out their assets, income, pensions and debts honestly, so the other is agreeing with their eyes open. An agreement signed in ignorance of what the wealthier partner actually owns is on weak ground.

Fairness, especially meeting needs and children's needs

Even a technically perfect agreement will not be enforced to the extent it is unfair. The court's overriding concern, exactly as in any divorce financial settlement, is that both people's needs, and any children's needs, are met. An agreement that would leave one spouse unable to house themselves, or a child without proper provision, will be departed from to that extent.

How to maximise enforceability

The practical checklist that family lawyers work to, drawn from Radmacher and the cases since, is straightforward:

• Sign well before the wedding. A widely used benchmark is at least 28 days before the ceremony, so there is no suggestion of pressure. A postnup avoids this timing issue because there is no wedding deadline.
• Give full and frank financial disclosure. Exchange a clear schedule of assets, income, pensions and debts, and attach it to the agreement.
• Take separate independent legal advice. Each person instructs their own solicitor, not a shared one. Same-solicitor arrangements create a conflict of interest and defeat the purpose.
• No duress or undue influence. Both people enter the agreement of their own free will, without threats or an ultimatum.
• Make the terms fair and needs-based. An agreement that provides properly for both people, and for children, is far more likely to be upheld than one that strips one partner of everything.
• Review it periodically. Revisit the agreement after major events, such as the birth of a child, buying a home, or a big change in wealth. A review clause and updates show the agreement still reflects the couple's intentions.

What a prenup or postnup can and cannot do

An agreement is a powerful tool, but it has firm limits. The table below summarises where a nuptial agreement carries weight and where it does not.

A prenup or postnup can	A prenup or postnup cannot
Record how the couple intend to divide assets and ring-fence specific property, such as a business, a pre-marital pension or an inheritance	Oust the court's jurisdiction; no clause can remove the court's power to make a financial order
Provide strong evidence of what was agreed, which a court will usually follow if the terms are fair	Leave a spouse or children in real financial need; such terms are overridden to that extent
Give both people certainty and reduce the cost and conflict of a future dispute	Bind the court on child arrangements or child maintenance, which are for the court and the statutory scheme
Protect provision for children from an earlier relationship, a common motive in second marriages	Guarantee an outcome if it would be unfair; the court keeps a safety valve under the Radmacher test

What it can do

• Record how the couple intend to divide assets, and ring-fence specific property such as a business, a pension built up before the marriage, or an inheritance.
• Provide strong evidence of what was agreed, which a court will usually follow if the terms are fair.
• Give both people certainty and reduce the cost and conflict of a future dispute.
• Protect provision for children from an earlier relationship, which is a common motive in second marriages.

What it cannot do

• Oust the court's jurisdiction. No clause can remove the court's power to make a financial order. Any attempt to do so is simply ignored.
• Leave a spouse or children in real need. Terms that would leave someone unable to meet reasonable needs, or that fail to provide for children, will be overridden to that extent.
• Bind on child arrangements or child maintenance. Decisions about children are for the court and, for maintenance, largely for the statutory scheme; a nuptial agreement cannot fix them in advance.

What they cost

For a straightforward agreement, most people should budget in the region of £1,000 to £3,000 plus VAT per person. That figure typically covers a solicitor drafting the agreement for one party and a separate solicitor providing independent legal advice to the other. Fixed-fee packages are common at the simpler end of the market.

Costs rise where the finances are complex, for example where there are business interests, trusts, overseas assets or significant pensions, because both the disclosure exercise and the drafting take longer. A postnup costs broadly the same as a prenup. Set against the potential cost of a contested financial dispute later, which can run into tens of thousands of pounds, an agreement is often the cheaper option in the long run. For context on those wider costs, see our guide to the divorce financial settlement process and the tools on our financial settlements hub.

When they matter most

Prenups and postnups are not just for the very wealthy. They earn their keep in specific situations:

• Second marriages. Where one or both people have children from a previous relationship, an agreement can help preserve provision for those children and protect assets built up before the new marriage. This is one of the most common reasons couples put an agreement in place, and it often pairs with over-50s financial planning; see our guidance for the over-50s and divorce.
• Business owners. If you own or co-own a company, an agreement can help protect the business from being broken up or heavily diluted in a future settlement, and can sit alongside shareholder arrangements. This is a technical area in its own right, covered in our guide to business assets and limited companies in divorce and our resources for business owners.
• Inherited or pre-marital wealth. Where one person brings substantial assets into the marriage, or expects a significant inheritance, an agreement records the intention to keep those assets separate, which a court can then take into account.
• Large disparity in assets. Where one partner is far wealthier than the other, an agreement gives both people clarity about what would happen, rather than leaving it entirely to the court's discretion years later.

Speak to a specialist

A prenuptial or postnuptial agreement is only as good as the way it is prepared, and the enforceability conditions leave little room for shortcuts. Crucially, each person needs their own independent legal advice from a separate solicitor: it is not only sensible, it is one of the requirements that makes the agreement stand up. This article is information, not legal advice, and every couple's circumstances differ. Our team works with experienced family law professionals across England and Wales who prepare and review nuptial agreements. Tell us a little about your situation using our contact form and we will connect you with a specialist for a no-obligation conversation about your options. We are not a law firm and we do not give legal advice; we may receive a fee from the firm we introduce you to, which never affects what you pay or the advice you receive.