Joint wills explained: can couples still use them?

A joint will allows two people to record their wishes in one document, but it is rarely recommended in modern UK estate planning. While many couples believe a single document locks their inheritance wishes in place forever, the legal reality is different. A surviving spouse can change or revoke a joint will entirely after the first partner dies, unless there is written evidzence of a binding agreement. This creates ambiguity, legal disputes, and inflexibility when circumstances change. This guide explains what a joint will actually does, whether it is legally binding, the real risks involved, and why mirror wills or mutual wills may be better options for most couples. Given how easily things can become complicated, it’s often worth speaking to a wills and probate solicitor to make sure your wishes are clear, protected, and won’t be challenged later on.

Quick Answer: What’s the difference between joint, mirror, and mutual wills?

• A joint will is one document signed by two people but is not automatically binding on the surviving spouse unless there is written evidence of a binding agreement.
• Mirror wills are two separate documents that are fully flexible, while mutual wills are binding agreements that lock in the surviving spouse’s inheritance arrangement after the first dies.
• Joint wills create ambiguity and legal risk; modern practice favours separate, clearly documented wills instead.

Understanding which type of will suits your family’s circumstances requires specialist advice. Speak with a qualified wills and probate solicitor to protect your legacy and avoid costly disputes.

What are joint wills?

A joint will is a single document signed by two people (usually a married couple or civil partners) that sets out how both their estates will be distributed after death.

How a joint will works in practice:

• Single document: Both testators (will-makers) sign the same will, not separate ones.
• Combined wishes: The will deals with both people’s property and assets within the same document.
• Witnessed together: Both signatories must sign in the presence of two independent witnesses.
• Witness eligibility: Witnesses (and their spouses or civil partners) should not be beneficiaries, or any gift to them may fail.

Example:

Emma and Joe create a joint will saying their house goes to the other spouse, then to their children. This single document sets out both their wishes in one place.

Are joint wills legally binding?

No, a joint will is not automatically binding on the surviving partner after the first person dies, unless there is written evidence of a binding agreement.

Many people assume that because two people signed the same document, it locks them both in forever. The law is different. Under Section 9 of the Wills Act 1837, a will, including a joint will, can be revoked or changed at any time by the testator, as long as they have testamentary capacity and act voluntarily.

What the courts have said:

In Legg v Burton (2017) EWHC 2088 (Ch), the High Court examined the distinction between joint wills and mutual wills. The judge confirmed that unless there is clear evidence of a binding agreement, a joint will is simply two wills in one document; each person’s share can be altered independently. The court held that mutual wills (a true binding agreement) require proof of a contract, which is rarely evident in simple joint wills.

Can a surviving spouse change a joint will?

Yes, a surviving spouse can change a joint will after the first partner dies; this is the most significant practical issue with this arrangement.

What typically happens after the first death:

• The surviving partner inherits as set out in the joint will (if they choose to follow it).
• They are then free to create a completely new will, leaving assets to different beneficiaries.
• They can exclude children, remarry and benefit a new spouse, or alter any provision.
• There is no legal obligation to honour the original joint will arrangement unless it was a binding mutual will.
• The first deceased’s family has no legal recourse unless they can prove the joint will was actually a mutual will with a binding contract.

Real-world scenario:

John and Mary make a joint will, each leaving everything to the other, then equally to their two adult children. John dies. Mary inherits everything. Mary then remarries and creates a new will leaving all assets to her new husband, excluding John’s children entirely. Unless John and Mary had a written binding agreement (making it a mutual will), the children have no legal claim.

Joint wills vs mirror wills vs mutual wills: key differences

Learning the differences between these three types is essential; they sound similar but have very different legal effects:

Why joint wills are rarely used today: the real risks

Many solicitors advise against joint wills because the risks outweigh the apparent simplicity, and they may create more problems than they solve.

• Ambiguity over intention: A single document signed by two people creates uncertainty about whether both parties intended to be bound together or remain free to change independently. Resolving this ambiguity through litigation is expensive and unpredictable.
• Disputes after both partners die: Children from different relationships may argue whether the joint will was binding or revoked by a new will, leading to years of costly litigation while the estate is frozen.
• Inflexibility if circumstances change: A surviving spouse facing care fees, financial hardship, or major life changes may need to adjust their will but remain uncertain whether they can do so legally without triggering disputes.
• Difficulty enforcing or defending changes: If a surviving spouse creates a new will, other family members may challenge it by arguing the original joint will was binding, forcing the survivor to defend their right to change it at significant cost.
• Professional caution: Many solicitors decline to draft joint wills because the risks are well documented in case law and create exposure to negligence claims or complaints.
• Unclear revocation: It may be ambiguous whether a new will fully revokes the joint will or only the survivor’s share, leading to disputes over which provisions still apply.

FAQs

Can a surviving spouse change a joint will?  Yes, unless there is written evidence the joint will was a binding mutual will. A surviving spouse can create a new will, revoke the original entirely, or modify any provision. This is the central weakness of joint wills; they offer no enforceable guarantee the survivor will honour the original arrangement.

What happens to a joint will if we divorce? In England and Wales, divorce usually revokes gifts and executor appointments to a former spouse, treating them as if they had died. The rest of the will may still operate, but the outcome can be unintended, especially if most assets were left to the former spouse. You should make a new will as soon as divorce or separation is likely.

Can a joint will be contested? Yes. Joint wills can be more vulnerable to challenge because their ambiguous structure may invite disputes. Contested joint wills can lead to years of litigation costing £5,000–£50,000+. Clear separate documents reduce this risk significantly.

A joint will offers no enforceable protection for your family’s inheritance. Modern practice favours mirror wills (flexible) or mutual wills (binding). Professional advice costs £200–£400 and prevents disputes costing thousands. Clarify your options today with a qualified solicitor.

This article provides general legal information only and is not a substitute for professional legal advice. Consult a qualified solicitor for your specific circumstances.

Protect your legacy

Qredible’s network of specialist wills and probate solicitors provides expert guidance tailored to your circumstances, whether you need to clarify an existing joint will, draft mirror wills, or create binding mutual wills.

NEXT STEPS:

• Clarify what you have: Review your existing will to understand whether it is a joint will, mirror wills, or mutual wills. If unclear, a solicitor consultation costs £100–£200.
• Decide what you need: Choose between mirror wills (flexible), mutual wills (binding), or mirror wills with trusts (asset protection) based on your family situation.
• Get professional advice: Consult a wills and probate solicitor to draft new wills or clarify your current arrangements. Fixed fees typically range from £200–£400.
• Document binding agreements in writing: If you want a mutual will, ensure your solicitor creates a written binding agreement so there is no future ambiguity.
• Review regularly: Update your will every 3–5 years or after major life changes (marriage, divorce, children, significant asset changes).