Prenuptial & cohabitation agreements — planning before things go wrong
REVIEWED BY: Sean McNamara on 2026-08-28
The legal starting point
Prenuptial agreements are not automatically binding in England & Wales — but since the landmark Radmacher case (2010), courts give them decisive weight if they are fair, both parties entered them freely with full understanding, and needs are met. In practice a well-made pre-nup is usually upheld. Cohabitation agreements between unmarried partners are generally enforceable as contracts.
What makes an agreement likely to be upheld
1. Both parties took legal advice (independently) before signing 2. Full financial disclosure — both sides knew what the other had 3. Signed well before the wedding (ideally 28+ days; the pressure of the wedding eve is a red flag) 4. Fair, and meeting needs — especially of children; no one left destitute 5. No duress or misrepresentation 6. Reviewed on major life changes (children, serious illness, huge wealth shifts)
What cannot be excluded
- Children's interests — the court will always provide for children's needs regardless of the agreement (child arrangements and child maintenance are governed by separate law)
- Needs-based minimums — the court retains ultimate discretion
Cohabitation agreements (unmarried couples)
More important than pre-nups in some ways, because cohabitants have no automatic rights at all (see our cohabitation guide). A cohabitation agreement can settle: ownership shares, contributions to mortgage/bills, what happens on separation, pets, and personal possessions. Pair it with a declaration of trust for the house and wills for inheritance.
Postnuptial agreements
Made after marriage — same enforceability logic as pre-nups (Radmacher applies). Often used to paper an agreement reached during a wobble, or after receiving an inheritance.
How to get one
- Both parties need independent advice (solicitors; see our finding-a-solicitor page)
- Full disclosure in writing, attached as a schedule
- Costs are typically a few hundred to a few thousand pounds each — trivially cheap against a contested financial remedy case
Official links
- https://www.gov.uk/money-property-when-relationship-ends
- Cohabitation: https://www.gov.uk/living-together-and-marriage
This page is general information, not legal advice. YourFamilyCase.co.uk is an independent information directory and is not affiliated with HMCTS or gov.uk.
Content verified against the official HMCTS court directory, gov.uk forms and fees pages, and the professional body registers (SRA, FMC, Bar Council). Last reviewed September 2026.