However carefully a prenup is drafted, there is one limit it can never get around: it cannot leave a partner – or any children – in real financial need. This “needs” principle is the single most important thing to understand about how far a prenup can actually go. It is the backstop the court keeps whatever the document says, and it explains why a fair, realistic agreement is far more powerful than a greedy one.
This guide explains what “needs” means in family law, why a prenup cannot override it, how needs are judged, and how to write an agreement that works with the principle rather than against it.
What “needs” means
In family law, “needs” is about meeting the genuine requirements of both partners and their children – principally somewhere suitable to live and enough income to live on. It is not a fixed figure; it is judged against the standard of living during the marriage, the length of the relationship, the partners’ ages and earning capacities, and any responsibilities for children. A short, childless marriage between two earners produces very different “needs” from a long marriage in which one partner gave up work to raise a family (see prenups and the stay-at-home parent).
Why a prenup cannot override it
This flows directly from the fact that prenups are not automatically binding. Under the Matrimonial Causes Act 1973 the court’s job is to reach a fair outcome, and Radmacher v Granatino made clear that respect for an agreement gives way where holding a couple to it would be unfair. An agreement that would leave one partner with nothing to live on is, by definition, not fair – however clearly it was written, however freely it was signed. So the court will follow a prenup as far as it fairly can, then top up provision if needed to meet someone’s needs.
Needs, sharing and compensation
It helps to know that the law recognises three broad strands in a financial settlement: needs, sharing (of assets built up during the marriage) and compensation (for a relationship-generated disadvantage, such as giving up a career). A prenup has the most room to work on the sharing strand – agreeing that certain assets stay separate rather than being shared (see matrimonial vs non-matrimonial property). What it cannot do is contract out of needs. In practice, the more surplus there is above both partners’ needs, the more a prenup can protect – which is why they are so effective for higher-net-worth couples and for ring-fencing specific assets like a business or an inheritance.
What this means when you write your prenup
The practical lesson is to be realistic. A prenup that protects specific assets – a business, an inheritance, property owned before the marriage – while still making fair provision for both partners is far more likely to be followed than one that tries to give one partner everything and the other nothing. Some pointers:
- Provide a genuine floor for the financially weaker partner – housing and income – rather than leaving them exposed.
- Leave room for children, since their needs come first (see prenups and children).
- Build in a review clause so the agreement keeps pace with changing needs over a long marriage.
- Aim for terms that are fair – an agreement that respects needs is one a court will respect in turn.
Working with the needs principle makes a prenup stronger
It is tempting to see needs as a weakness in the system – the reason a prenup is not a cast-iron guarantee. In fact, working with it is what makes a prenup worth having. A fair agreement is a followable one: because it stays on the right side of needs, a court has every reason to hold the couple to it. An agreement that ignores needs invites a challenge and may be disregarded wholesale – so the greedy version is actually the weaker one.
How needs play out in practice
A few illustrations show how the principle bites differently depending on the circumstances:
- Short marriage, two earners, no children. Needs are modest, so a prenup ring-fencing pre-owned assets is likely to be followed closely (compare short marriages).
- Long marriage, one partner gave up work to raise a family. Needs are substantial – housing and income – and a court may look beyond a prenup that left that partner with little (see stay-at-home parents).
- Very wealthy couple with assets far above needs. There is plenty of surplus to protect, so a prenup can shield a great deal while still meeting needs generously (see high-net-worth prenups).
The common thread: the more a couple has above the needs line, the more a prenup can protect – and the more careful you must be to leave the weaker partner a genuine floor.
How a court actually assesses needs
“Needs” sounds vague, but in practice a court approaches it methodically. It starts with housing: where will each partner, and any children, live, and what does suitable housing cost in the area they realistically need to be? Then income: what does each partner need to meet day-to-day outgoings, and what can each earn, now and in future? A partner who has been out of the workforce raising children will not instantly command their old salary, and the court factors in that reduced earning capacity. Finally it looks at the resources available to meet those needs – the pool of assets and income the couple actually have. The bigger that pool, the more generously needs can be met and the more surplus is left over for a prenup to allocate. This is why the same agreement can be enforced almost to the letter for a wealthy couple and heavily adjusted for a couple of modest means: it is not that the prenup is treated differently, but that there is less room above the needs line to work with (compare how assets are divided on divorce).
Needs change over the life of a marriage
One of the reasons needs cannot be signed away in advance is that they are a moving target. A childless couple in their late twenties, both earning, have modest needs; the same couple twenty years later, with children, a larger home and one career sacrificed, have very different ones. An agreement written for the first situation can look harsh when measured against the second – which is exactly why fairness is judged at the divorce and why a review clause earns its place. Some couples go further and build in provision that grows with the length of the marriage or the arrival of children, sometimes using a sunset clause so that protection tapers over time. These are ways of designing an agreement that anticipates changing needs rather than ignoring them.
Meeting needs does not mean giving up protection
It is worth stressing, because couples often fear the opposite, that respecting the needs principle does not gut a prenup of its value. The two most powerful uses of a prenup – ring-fencing assets you brought into the marriage and protecting things like an inheritance, a business or a pension – all still work, provided the outcome leaves the other partner properly housed and supported. In many cases the needs can be met from income or from the shared, marriage-built assets, leaving the protected assets largely intact. Far from being a loophole that swallows the agreement, needs is simply the floor beneath which you cannot push the other partner – and a sensible prenup is designed to sit comfortably above it (see matrimonial vs non-matrimonial property).
The needs principle: the limit on every prenup
The needs principle is the one rule no prenup can get around: a court will always make sure both partners – and any children – have somewhere suitable to live and enough to live on, whatever the agreement says. Far from weakening a prenup, working within it is what makes one followable: an agreement that protects specific assets while meeting needs is the kind a court will respect and uphold.
Where the needs principle comes from
The needs principle is not a judicial habit; it is in the statute and in the leading case. Section 25 of the Matrimonial Causes Act 1973 requires the court, when deciding financial provision on divorce, to have regard to all the circumstances, giving first consideration to the welfare of any child of the family under eighteen, and then to a list that begins with each party's income, earning capacity and resources and continues with their financial needs, obligations and responsibilities and the standard of living during the marriage. Section 34 of the Matrimonial Causes Act 1973 makes void any term of an agreement that tries to restrict the right to apply to the court for that provision. Together they mean a prenup can shape how the court exercises its discretion but cannot remove the discretion or the needs assessment that sits at its centre.
In Radmacher v Granatino the Supreme Court set the principle inside its test: an agreement freely entered into with a full appreciation of its implications will be given effect unless it would be unfair to hold the parties to it, and the court identified need as the clearest case of unfairness. It said an agreement is likely to be unfair if it would leave one party in a predicament of real need while the other enjoys a sufficiency, and that an agreement cannot prejudice the reasonable requirements of any children. Where those conditions do not bite, the court added, fairness may well not require any departure from the agreement at all.
The 2025 decision in Standish v Standish shows how the principle sits with the sharing rules. The sharing principle applies to matrimonial property and not to non-matrimonial property, so a prenup that ring-fences pre-marital assets is working with the law; but needs can be met from any asset, non-matrimonial included, where the shared property is not enough. That is the precise sense in which needs is the limit on every prenup: it caps what ring-fencing can achieve, and an agreement that provides for both partners' reasonable needs is one the court has no reason to disturb.
The needs principle: FAQs
Can a prenup leave one partner with nothing?
No – the needs principle prevents that; a court will top up provision to meet reasonable needs (see when is a prenup unfair?).
How are needs judged?
Against the standard of living during the marriage, the length of the relationship, ages, earning capacities and responsibility for children.
Can a prenup still protect a business or inheritance?
Yes – needs limits how much you can take from a partner, but a fair prenup can still ring-fence specific assets (see inherited wealth).
Do children affect the needs assessment?
Very much – their needs come first, and can drive housing and support for the parent caring for them (see prenups and children).
Does a long marriage change how needs are met?
Yes – the longer the marriage and the greater the sacrifices, the larger reasonable needs tend to be, which is why a review clause helps.
Would qualifying nuptial agreements remove the needs limit?
No – even the proposed qualifying nuptial agreements would keep needs as a backstop.
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UK Prenup is not a law firm and does not provide legal advice. A prenuptial agreement in England & Wales is not automatically binding, and both partners should take independent legal advice before signing.