Mirror Wills vs Single Will: Which Do You Need?

The most common question people ask when starting a will is a simple one: do I need a single will, or should I get mirror wills with my partner? The answer depends almost entirely on your relationship status and whether you and a partner share the same wishes about who should inherit. This guide walks you through both options clearly, so you can choose the right one without second-guessing yourself.

Quick answer: which do you need?

What is a single will?

A single will is a legal document made by one person that sets out what they want to happen to their estate when they die. It names the beneficiaries (the people who will receive your assets), the executor (the person responsible for administering the estate), and, if relevant, guardians for any children under 18. It can also include specific gifts of money or personal items.

A single will has no connection to any other person's will. It stands entirely on its own. You can leave your estate to whoever you choose — a partner, children, siblings, friends, a charity, or any combination. You can update it at any time and it remains valid until you revoke it or it is automatically revoked by marriage.

A single will is the right choice for a wide range of people. You do not have to be single in the dating sense to need a single will — you might simply have very different wishes from your partner, or you may be making a will as an individual measure while a relationship is still developing.

Who a single will suits

A single will is typically the best fit for people who are not in a committed, long-term partnership, or whose estate planning needs to operate independently from a partner's. This includes people who are single or widowed and want to leave their estate to children, siblings, or other family members. It also includes recently divorced people who need to update their arrangements after a marriage has ended, since a divorce does not automatically rework your entire will — only gifts to the former spouse are treated as lapsed.

It is also the right product if you are in a couple but you and your partner have decided to handle your wills separately, perhaps because you have very different beneficiaries in mind, or because one of you already has a will from a previous arrangement.

What are mirror wills?

Mirror wills are two separate will documents — one for each partner — that are written to complement each other. They "mirror" each other in their main provisions: typically, each partner leaves their entire estate to the other, and if the surviving partner has already died, the estate passes equally to the children or other named beneficiaries.

The two documents are legally independent. They are not joined together, and they are not mutually binding. Either partner can change or revoke their will at any time, without consulting or informing the other. This is a crucial point that many couples misunderstand, and we return to it in detail below.

Mirror wills are particularly important for cohabiting couples. Under the intestacy rules in England and Wales, an unmarried partner has no automatic right to inherit anything from your estate if you die without a will, no matter how long you have lived together. The law does not recognise "common law marriage" — that is a myth. Mirror wills are the simplest way to ensure that each partner is protected.

Who mirror wills suit

Mirror wills are designed for couples whose wishes about inheritance broadly align. They work well for married couples, civil partners, and cohabiting partners who want to leave everything to each other with the same secondary beneficiaries (usually children) after both have died. They are especially valuable when you have children together and need both wills to name the same guardians, so there is no ambiguity if both parents die in the same incident.

Side-by-side comparison

Common scenarios with recommendations

Married couple with children

Mirror wills are almost always the right choice here. You can leave everything to each other first, then equally to your children if the surviving partner has also died. Both wills name the same guardians, so if the worst happens and you both die at the same time, the children's care is clearly accounted for. The mirror wills kit at £59.99 gives you both documents in one purchase.

Unmarried individual with no partner

A single will is exactly what you need. You choose your own beneficiaries — perhaps siblings, parents, friends, or a charity — and appoint an executor to handle the estate. There is no partner to coordinate with, so there is no reason for a second document. A single will kit gives you everything required for £39.99.

Recently divorced person

Make a new single will as soon as possible after your divorce is finalised. Under s18A of the Wills Act 1837, any gifts in your existing will to your former spouse and any appointment of them as executor are automatically treated as if the former spouse had predeceased you, from the date of the divorce. However, the rest of your will still stands, which may not reflect your current wishes at all. A clean, new single will avoids any ambiguity and ensures your estate goes exactly where you want it to go.

Cohabiting couple

Mirror wills are strongly recommended, and the sooner the better. As an unmarried couple, you have none of the automatic inheritance protections that married couples enjoy. Under the intestacy rules, your partner's estate would pass to their blood relatives — not to you — if they died without a will. Mirror wills put that right immediately. It is also worth knowing that if you do not have a will and your partner is not a co-owner of your property, they may not even be able to stay in your shared home after you die while the estate is sorted out. Do not delay this.

Myth: mirror wills are legally binding on the survivor

This is one of the most persistent misunderstandings about mirror wills, and it is important to clear it up. Mirror wills are not mutually binding. They are two separate, independent legal documents. After the first partner dies, the surviving partner is completely free to write a brand-new will, leaving their estate to whoever they choose. They do not need the deceased partner's permission, and there is no legal mechanism that locks the survivor into the original arrangement.

This means it is theoretically possible for a surviving partner to remarry, make a new will leaving everything to a new spouse, and your children from the original relationship could end up with nothing. This is not a flaw unique to DIY wills — it applies to any mirror wills, even those drafted by solicitors, unless a specific protective structure (such as a life interest trust) is put in place.

The concept of a binding arrangement between partners in a will is called a "mutual will", which is a different and much more complex product. Mutual wills create a contractual obligation that prevents the survivor from changing the will after the first partner dies. They are rare, involve specialist legal advice, and are only suitable in very specific circumstances. For the vast majority of couples, mirror wills — combined with open communication and trust — are the right, practical solution.

When to involve a solicitor

A DIY will kit is perfectly adequate for most people with a straightforward estate. However, there are situations where professional legal advice is genuinely worthwhile and, in some cases, essential:

• •Blended families. If you or your partner have children from previous relationships, there is a real risk that the surviving partner could disinherit the deceased partner's children after remarrying or updating their will. A solicitor can advise on life interest trusts and other structures that protect children from both sides of the family.
• •Trusts. If you want to hold assets in trust for minor children, or set up a discretionary or protective trust for a vulnerable beneficiary, a solicitor should draft the trust provisions. The wording needs to be precise and the trustee obligations are significant.
• •Business assets. Business property relief and shareholder agreements interact with your will in complex ways. If you own shares in a private company, are a sole trader, or are in a partnership, take professional advice.
• •Large or complex estates. If your combined estate may be subject to inheritance tax (currently above £325,000 per person, or £500,000 with the residence nil-rate band), a solicitor or financial adviser can help you structure your wills to minimise the tax burden.
• •Foreign property or non-UK domicile. If you own property abroad or if either partner is not domiciled in the UK, you will need legal advice covering multiple jurisdictions.

For everyone else — the majority of people making their first will or updating an existing one — a well-structured DIY will kit, completed carefully and signed correctly, is a reliable and legally valid solution.

Frequently asked questions

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