Post-nuptial Agreements: A Practical Guide (England & Wales)

At a glance

• Not automatically binding, but courts give decisive weight to a post-nuptial agreement freely entered into with a full appreciation of its implications, unless it would be unfair to hold the parties to it — the test set out by the Supreme Court in Radmacher v Granatino [2010] UKSC 42.
• The court's statutory jurisdiction is never removed. On divorce, financial matters are decided under the Matrimonial Causes Act 1973, and the court must still have regard to the section 25 factors — including the welfare of any child of the family under 18, which comes first.
• Timing is the key difference from a pre-nup: a pre-nuptial agreement is signed before the wedding, a post-nuptial agreement afterwards. See our guide to pre-nuptial agreements for that comparison.
• A post-nup is not the same as a separation agreement. A post-nup is forward-looking and signed while the marriage continues; a separation agreement is signed once a couple has actually separated and deals with the present, not a hypothetical future.
• Four things courts weigh most heavily: full and honest financial disclosure by both spouses, independent legal advice for each spouse, the absence of any pressure or unfair advantage-taking when it was signed, and whether the outcome remains fair by the time of the divorce.
• Civil partners are covered by the same principles, under Schedule 5 to the Civil Partnership Act 2004 rather than the Matrimonial Causes Act 1973.
• Provisions about children are never binding on the court — a judge decides child arrangements and financial provision for children based on welfare at the time, not on what parents agreed in advance.

What is a post-nuptial agreement?

A post-nuptial agreement is a written contract signed by two people who are already married to each other. Its purpose is to record, in advance, how they intend their finances to be handled if the marriage were ever to break down. That typically covers who keeps which property, how joint assets would be split, whether spousal maintenance would be paid, and how debts would be allocated.

Unlike in some other jurisdictions, a post-nuptial agreement is not automatically binding in England & Wales. The family court retains the final say over financial matters on divorce under the Matrimonial Causes Act 1973, and it must have regard to the factors set out in section 25 of that Act — including the parties' income, needs, standard of living, ages, contributions to the marriage, and, first and foremost, the welfare of any child of the family under 18.

That said, courts do not start from a blank sheet. Since the Supreme Court's landmark decision in Radmacher v Granatino [2010] UKSC 42, the courts have given real weight to nuptial agreements — pre- or post-marriage — where both parties entered into them freely, with a full understanding of the implications, and where holding them to the agreement would not be unfair. The Supreme Court was clear that this principle applies equally to post-nuptial agreements; there is no material difference in how the fairness test is applied simply because the agreement was signed after the wedding rather than before it.

In practice, that means a carefully prepared post-nuptial agreement is far from worthless. It is often highly influential in how a court approaches a later financial dispute, particularly where there are no children involved and both spouses had independent legal advice before signing.

Is a post-nuptial agreement legally binding? The Radmacher test

The Radmacher test asks three broad questions: was the agreement entered into freely, did each spouse have a full appreciation of what they were agreeing to, and would it be unfair, in the circumstances at the time of the divorce, to hold them to it? Because the court cannot be contracted out of its statutory jurisdiction, it will still run the section 25 exercise — but a fair, freely made agreement is usually treated as the court's starting point rather than something to be argued around.

Nothing in the Matrimonial Causes Act 1973 mentions nuptial agreements directly; their weight comes from case law applying the general section 25 discretion, not from a standalone statutory route to enforceability. That is why the practical safeguards below matter so much — they are what persuades a court to follow the agreement rather than reopen it.

What a post-nuptial agreement can (and can't) cover

Most post-nuptial agreements deal with some combination of the following:

• Property. How the family home, any second properties, and pre-marital property owned by either spouse would be dealt with.
• Pensions. Whether pension sharing would apply, and to what extent, given that pensions are frequently one of the largest assets in a marriage.
• Business interests. Protecting a business one spouse built up, particularly where the other spouse has no involvement in it.
• Inheritances and gifts. Ring-fencing money or property received from family, which courts often treat differently from assets built up jointly during the marriage.
• Spousal maintenance. Whether ongoing maintenance would be paid, for how long, and on what basis — though the court can still depart from this if it would leave a spouse in real need.
• Debts. How any liabilities, joint or individual, would be allocated between the parties.

What it cannot do is bind the court on anything concerning children — arrangements for where children live, how much time they spend with each parent, or child maintenance are decided on welfare grounds at the time, never by a prior agreement between the parents. It also cannot remove the court's overriding duty to consider fairness under section 25, however clearly the terms are drafted.

Post-nuptial agreement vs pre-nuptial agreement vs separation agreement

The three documents are often confused because they cover similar financial ground. The table below sets out the practical difference.

| Document | When it's signed | What it's designed to do | Legal status | |---|---|---|---| | Pre-nuptial agreement | Before the wedding | Sets out how finances would be handled if the marriage later ends | Not automatically binding; assessed under the Radmacher fairness test | | Post-nuptial agreement | At any point after the wedding | Sets out how finances would be handled if the marriage later ends | Not automatically binding; assessed under the same Radmacher fairness test | | Separation agreement | Once the couple has actually decided to separate | Records how finances and arrangements will be divided now, not hypothetically | Not automatically binding, but courts give it significant weight where fairly negotiated with disclosure and advice |

See our guides to pre-nuptial agreements and separation agreements for the detail on each.

Why couples choose to enter into a post-nuptial agreement

There is no single trigger for a post-nup, but some circumstances come up repeatedly:

• A couple didn't have time for a pre-nup. Wedding planning is busy, and the legal advice and disclosure a proper pre-nuptial agreement requires can get squeezed out. A post-nup, signed soon after the wedding, is a common fallback.
• An inheritance or windfall arrives. One spouse receives a significant inheritance, a business is sold, or a windfall changes the couple's financial picture, and both want clarity on how it would be treated.
• One spouse starts, grows, or sells a business. Where a business is built up largely by one spouse during the marriage, a post-nup can record how it would be treated on divorce, protecting the enterprise (and, often, jobs that depend on it) from being disrupted by a later dispute.
• A spouse steps back from paid work. If one spouse gives up or reduces work — commonly to care for children — a post-nup can record what financial support would look like, giving the party who stepped back some security.
• Reconciling after a difficult period. Some couples use a post-nup as part of rebuilding trust after a rocky patch, setting out clear financial expectations going forward.
• A blended family. Where one or both spouses have children from a previous relationship, a post-nup can help protect what each intends to pass on to their own children.

How courts decide what weight to give an agreement

The factors that most often decide how much weight an agreement is given are:

• Full and honest financial disclosure. Each spouse should have set out a complete picture of what they own and owe before signing. Non-disclosure is one of the most common grounds on which an agreement is later challenged.
• Independent legal advice on both sides. A spouse who signed without their own solicitor advising them will find it far easier to argue afterwards that they did not understand what they were giving up.
• No undue pressure. An agreement signed under emotional pressure, in a rush, or without a reasonable opportunity to consider it, is far more vulnerable to being set aside.
• Fairness at the point of divorce, not just at signing. An agreement that leaves a spouse — or, especially, children — without their needs met is unlikely to be enforced as drafted, however fairly it was negotiated at the time.

When a court is likely to depart from the agreement

A court may depart from the terms of a post-nuptial agreement where one or more of the safeguards above were missing, or where enforcing it would produce a genuinely unfair outcome. Common grounds include inadequate disclosure at the time of signing, one party having no independent legal advice, evidence of pressure or a rushed signature, and — perhaps most commonly of all — an agreement that has simply aged badly. A document drafted when a couple had no children and modest assets can look very different a decade later, after a house purchase, a business sale, or the arrival of children. The court is still required to weigh the section 25 factors, including needs, standard of living, age, and contributions, when deciding what is fair overall, and it will not enforce an agreement that leaves a spouse or children without their needs met.

Civil partners: the same principles apply

Everything above applies with equal force to civil partners, not just spouses. Financial relief on the dissolution of a civil partnership is governed by Schedule 5 to the Civil Partnership Act 2004, which sets out factors that mirror section 25 of the Matrimonial Causes Act 1973 closely, including the welfare of any child of the family as the court's first consideration. A post-civil-partnership agreement is treated the same way as a post-nuptial agreement between spouses: capable of carrying decisive weight, but never automatically binding, and assessed against the same fairness principles drawn from Radmacher v Granatino.

Is reform on the way?

The rules above come from case law, not a dedicated Act of Parliament, and that has long been a source of debate among family lawyers. The Law Commission has examined this area more than once. Its most recent scoping report on financial remedies on divorce, published in December 2024, looked again at whether nuptial agreements should be placed on a firmer statutory footing as part of wider reform of the law on financial provision. A scoping report sets out problems and options rather than binding recommendations, and any change would ultimately need new legislation from Parliament. For now, the Radmacher fairness test under the existing case law remains the operative standard in England & Wales — always check GOV.UK and legislation.gov.uk for the current position before relying on any anticipated change.

How to put a post-nuptial agreement in place

1. Talk it through together first. Before any paperwork is drafted, both spouses need to have a frank conversation about why an agreement is being considered and what it should cover. Agreements that come as a surprise, or that one spouse feels pressured into, are the most likely to be challenged later under the Radmacher fairness test. Openness at this stage sets the tone for everything that follows.
2. Disclose finances fully and honestly. Each spouse should exchange a complete picture of what they own and owe: property, pensions, savings, investments, business interests, and liabilities. Without proper financial disclosure on both sides, a court is far more likely to give the agreement less weight later. Supporting statements and valuations should be attached as schedules.
3. Agree what the document should actually cover. Decide together how pre-marital assets, marital assets, inheritances, gifts, the family home, pensions, and any business interests should be treated. Think about whether spousal maintenance would apply, for how long, and in what circumstances. Clarity now prevents arguments later if the marriage ends.
4. Take independent legal advice, separately. Each spouse should instruct their own solicitor to advise them on the terms before signing. Shared lawyers, or one spouse going unadvised, is a well-known reason agreements are given less weight in court. Independent advice demonstrates that each party understood what they were agreeing to and signed willingly.
5. Sign, date, and store it properly. Once both parties are satisfied, the agreement should be signed, dated, and ideally witnessed. Keep the original somewhere safe and give a copy to each spouse.
6. Review it periodically. It is sensible to revisit the agreement every few years or after major life events — a new child, a house purchase, a business sale — because circumstances that made the terms fair at the time can shift, and a court is more likely to depart from terms that have become badly out of date. Record any updates in a signed variation, not an informal conversation.

This guide provides general information about post-nuptial agreements in England & Wales. It is not legal advice and is not a substitute for advice tailored to your specific circumstances. For general guidance on dividing finances on divorce, see GOV.UK: money and property when you divorce or separate.

Last reviewed: July 2026 by a non-practising solicitor · Next review due: July 2027 or on legislative change.