A postnuptial agreement ("postnup") in the UK is simply a prenup made after you are already married. It does the same job — setting out how you would divide money and property if the marriage ended — and the courts treat it on much the same basis as a prenup. If you have already tied the knot, it is not too late to get the clarity and protection a prenup offers; a postnup is the tool for exactly that. This guide explains how postnups work, when couples make one, how much weight they carry and what they cost.
What is a postnuptial agreement?
A postnup is a written agreement between a married couple (or civil partners) recording what each of them owns, what should stay separate, what is shared, and how their finances would be divided if they separated. The only real difference from a prenuptial agreement is timing — a prenup is signed before the wedding, a postnup after it. For a side-by-side comparison, see prenup vs postnup.
Do postnups carry the same weight as prenups?
Broadly, yes. The leading case on agreements, Radmacher v Granatino (2010), applies to both prenuptial and postnuptial agreements: a court should give effect to an agreement freely entered into by each party with a full appreciation of its implications, unless in the circumstances it would not be fair to do so. As with a prenup, a postnup is not automatically binding, and the court keeps its duty to meet needs and provide for children. See are prenups legally binding? and are postnups legally binding?
Interestingly, a postnup can be viewed as entered into with fewer pressures than a prenup, because there is no wedding day bearing down on the decision — which can actually strengthen the argument that it was signed freely.
When do couples make a postnup?
There are a handful of common triggers:
- They meant to make a prenup but ran out of time before the wedding.
- Their finances have changed — an inheritance, a new business, a property purchase.
- One partner is giving up work to raise children and both want fair provision agreed.
- They are reconciling after a difficult patch and want clarity going forward.
- They already have a prenup and want to update it as life moves on.
See also making a postnup years into a marriage and how to get a postnup.
How a postnup is made
The same good practice that makes a prenup robust applies to a postnup:
- Full and frank financial disclosure from both partners.
- Independent legal advice for each of you.
- Fair terms that meet both partners' needs.
- The agreement executed as a deed, signed in front of an independent witness.
For what to cover, see what to include in a prenuptial agreement — the same list applies to a postnup.
Postnuptial agreements in the UK: are they worth it?
For many couples a postnuptial agreement in the UK is well worth it. It brings the same clarity and protection as a prenup — over property, savings, a business or an inheritance — but can be made at any point in the marriage, with no looming wedding date to create pressure. That calm timing can actually help, because it makes it easier to show the agreement was entered into freely. The cost is modest next to a contested divorce, and you can update the agreement again later if your circumstances change.
Postnuptial agreement FAQs
Are postnuptial agreements legally binding in the UK?
Not automatically, but a fair postnup made with disclosure and advice is given significant weight (see are postnups binding?).
How much does a postnup cost?
Much the same as a prenup — from £199 online, or four figures via a solicitor (see postnup costs).
Can you get a postnup years after marriage?
Yes — you can make one at any stage of a marriage (see a postnup after years married).
Is a postnup as good as a prenup?
It is judged on the same principles and can be just as effective; the main thing is that it is fair and properly made (see prenup vs postnup).
Can a postnup be used to save a marriage?
Sometimes — agreeing finances can remove a source of conflict, and postnups are occasionally made during reconciliation (see a postnup after an affair).
Create your prenuptial agreement online
UK Prenup lets couples in England & Wales create a clear, fair prenuptial agreement online from £199, with your document generated instantly as a PDF. See how it works or get started.
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.