Mirror wills and second marriages: the risk to your children

What mirror wills are

Mirror wills are two wills in the same terms, one for each partner in a couple. The usual pattern leaves everything to the other, and if the other has died first, to the children equally. They are the most common wills made in England and Wales, they are quick to prepare, and for a couple with children only from their own relationship they usually do the job. Our guide to making a will covers the basics.

They are also two separate documents. Each partner has made their own will, and each will has one maker. Nothing in the mirror will structure links the two documents together, and nothing stops either maker from tearing theirs up the day after signing. Couples tend to assume the arrangement is a bargain, and it is that assumption that this guide is about.

Why they are not mutual wills

A mutual will is a will made under an agreement between two people that each will leave their estate in a particular way and that neither will revoke without the other's consent. Where such an agreement exists, the law gives effect to it: when the first dies having kept to the bargain, the survivor's estate is held on a constructive trust to carry out the agreed terms, and a later will by the survivor takes effect subject to that trust.

What makes a will mutual is the agreement, and the courts require clear evidence of it. In Re Cleaver, decided in 1981, the court found that the couple had agreed and gave effect to the arrangement; but the same line of cases makes plain that matching wills on their own prove nothing. Two people who make identical wills on the same day with the same solicitor, and who expect each other to keep to them, have made mirror wills unless they also agreed to be bound, and the burden of proving that agreement falls on whoever asserts it after the first death, usually a disappointed child.

Mutual wills can be made deliberately, by a clause in each will recording the agreement. They are rarely advisable. They bind the survivor to a will made possibly decades before their death, in circumstances neither partner could foresee, and the trust that arises on the first death is uncertain in its reach over assets the survivor acquires afterwards. The life interest trust described below achieves what most couples want from a mutual will without binding the survivor for life.

What the survivor can do

Under ordinary mirror wills, the survivor inherits everything outright on the first death. From that point it is the survivor's property. They can spend it, give it away, put it into a new joint account with a new partner, or leave it by a new will to anybody at all. The first partner's wishes about what should happen to it have no legal force once the estate has passed.

The survivor can also do nothing. Their existing mirror will still leaves everything to the children, and if they die without changing it, the children inherit. The risk is in the years between, and in the two events that change the position without the survivor doing anything deliberate.

Marriage revokes a will

Section 18 of the Wills Act 1837 provides that a will is revoked by the maker's marriage, and the same rule applies to a civil partnership. A widow who remarries at 68 has, at that moment, no will, whatever she signed with her first husband. If she dies without making a new one, her estate passes under the intestacy rules, and the new spouse takes the statutory legacy and half of the rest, with her children sharing the remaining half. Our guide to dying without a will sets out the figures.

The exception is a will made in contemplation of marriage. Section 18 says the will survives where it appears from the will that the maker was expecting to be married to a particular person and intended that the will should not be revoked by that marriage. The will has to say so, and it has to name the person. A general statement that the will should survive any future marriage does not work. Section 18(5) adds that converting a civil partnership into a marriage does not revoke a will made during the partnership.

The rule catches people who never intended anything by it. A survivor who remarries and assumes the old will still stands has replaced a will leaving everything to the children with an intestacy under which the new spouse takes most of the estate.

Sideways disinheritance

Sideways disinheritance is the name given to what happens to the children of a first relationship when the survivor's estate goes sideways to a new family. The children expected it to come down to them. It happens in three ways, and only one of them needs any bad intent.

The survivor remarries, the will is revoked, and the survivor dies without making another. The estate, which includes everything the first partner left, passes largely to the new spouse and then to the new spouse's family. The children of the first relationship receive half of whatever is above the statutory legacy, and may receive nothing at all if the estate is small.

The survivor remarries and makes a new will leaving everything to the new spouse, intending that the new spouse will look after the children. The new spouse may do so. The new spouse may instead leave everything to their own children, or remarry in turn, and the first family's inheritance disappears two steps down the line.

The survivor does not remarry, but forms a new relationship, moves the new partner into the house, and puts the money into joint names. Joint assets pass to the survivor of the joint holders on death regardless of the will, and the first family finds the estate that the will was supposed to distribute has already gone.

In each case the children's remedy is a claim under the Inheritance (Provision for Family and Dependants) Act 1975 against whichever estate the money ended up in, and adult children who were not financially dependent on the deceased have a hard time under that Act. The claim is expensive, uncertain and made against a step-parent. The drafting below is designed to make it unnecessary.

The life interest trust answer

The structure that solves sideways disinheritance is the life interest trust, and it is explained in full in life interest trusts in wills. In outline, each partner's will leaves their estate, or their share of the home, to trustees to hold for the survivor for life and then for the children. The survivor has the home to live in and the income from the investments. The capital never becomes the survivor's property, so a remarriage, a new will or a joint account cannot move it, and on the survivor's death it passes to the children of the person who made the will.

For inheritance tax, a life interest for a spouse under a will is an immediate post-death interest under section 49A of the Inheritance Tax Act 1984, the spouse is treated as owning the fund under section 49, and the spouse exemption applies on the first death exactly as it would to an outright gift. Using the structure adds no inheritance tax on the first death.

Where the couple own the home jointly, the will can only deal with the deceased's share if the ownership is as tenants in common. Joint tenants hold the whole together and the survivor takes everything by survivorship whatever the will says. Severing the joint tenancy, which is a short notice served by one owner on the other and registered at the Land Registry, is the first step, and it is often the step that is missed.

The trust can be drafted so that the survivor's life interest ends on remarriage or cohabitation, and so that the trustees can sell the house and buy another. Ending on remarriage is an option some couples take and others leave out. The survivor can also be given a power to take capital with the trustees' consent, where the couple want the survivor to have more than income if it is needed.

The allowances on second death

The figures below are gov.uk's, checked on 22 September 2026, and our guide to inheritance tax thresholds explains them in more depth.

Each person has a nil rate band of £325,000. Where the first to die leaves everything to the survivor, whether outright or on a life interest, the spouse exemption means none of that band is used, and the unused proportion transfers to the survivor's estate. Gov.uk confirms that any unused threshold can be added to the surviving partner's threshold on their death, so the survivor's estate has £650,000 before tax. The executors claim it on form IHT402 with the survivor's inheritance tax account.

The residence nil rate band is a further £175,000 per person, available where the home, or the proceeds of a home sold after 8 July 2015, passes to direct descendants, which gov.uk defines to include children, stepchildren, adopted and foster children and grandchildren. It too transfers: the unused percentage from the first death is added to the survivor's, and the transfer is available even where the first death was before the allowance existed in April 2017. That gives a couple up to £1 million in total on the second death where the home goes to the children. The allowance tapers by £1 for every £2 by which the estate exceeds £2 million, and the government's policy paper fixes all three figures until at least the end of the 2029 to 2030 tax year.

A life interest trust does not lose any of this. The fund is treated as part of the survivor's estate on their death, the transferred nil rate band is available against it, and where the home passes from the trust to the children on the survivor's death, the residence nil rate band applies because the children take on the death of a person who is treated as owning the home. The stepchildren point matters in a second marriage: the residence nil rate band is available where the survivor's home passes to the first partner's children, since a stepchild is a direct descendant for this purpose.

After a divorce

Divorce does something narrower than marriage. Section 18A of the Wills Act 1837 provides that where a marriage is dissolved or annulled, any appointment of the former spouse as executor or trustee, and any gift to the former spouse, take effect as if the former spouse had died on the date the marriage ended. The rest of the will stands. The same applies on the dissolution of a civil partnership.

So a mirror will made during the first marriage survives the divorce, with the former spouse cut out of it and the gift over to the children taking effect. That is often what the maker would want, and it is still worth reviewing, because a will drafted around a spouse who is now treated as dead may have no executor, may leave a gift to the spouse's family that still stands, and will say nothing about a new partner. Section 18A also preserves the former spouse's right to claim under the 1975 Act, which a clean new will and a financial order on the divorce together deal with.

A will made after the divorce and before a remarriage is revoked by the remarriage under section 18, so a person who divorces and remarries needs a will made in contemplation of the second marriage, naming the new spouse, or a new will after it. Our guide to changing a will covers the mechanics of a new will and a codicil.

Reviewing the wills

Mirror wills are made once and left. The events that undo them, a remarriage, a new relationship, a house put into joint names, a child's divorce, happen years later and rarely prompt anybody to look at the will. A couple with children from earlier relationships, or with any real prospect that the survivor might form a new one, should treat the standard mirror will as the wrong document and ask for the trust structure instead. A couple whose only children are their own can use mirror wills and should review them at every significant change.

Whichever applies, the review should check that the home is held as tenants in common if the will relies on that, that the executors and trustees are still the right people, that the letter of wishes matches the will, and that any will made before a marriage names the intended spouse. The wills check on this site runs through those questions, and the AD Wills service drafts either structure.

Frequently asked questions

What is the difference between mirror wills and mutual wills?

Mirror wills are two separate wills in matching terms, and either maker can change theirs at any time. Mutual wills are made under a binding agreement not to revoke, and after the first death the survivor's estate is held on trust to carry out the agreed terms. Courts require clear evidence of that agreement and will not infer it from the fact that the wills match, so a couple who simply expect each other to keep to their wills have made mirror wills.

Can my husband or wife change their will after I die?

Under ordinary mirror wills, yes. Everything passes to them outright on your death and becomes their property, and they can leave it by a new will to anybody, put it into joint names with a new partner, or lose it to an intestacy if they remarry and make no new will. If you want the capital fixed for your children, your will needs to leave it on a life interest trust for your spouse, which costs nothing in inheritance tax.

Does getting married cancel my will?

Yes. Section 18 of the Wills Act 1837 revokes a will on the maker's marriage or civil partnership, and the estate then passes under the intestacy rules unless a new will is made. The exception is a will that says it is made in contemplation of marriage to a named person and is intended to survive it. A general statement about future marriages does not work. Converting a civil partnership into a marriage does not revoke a will made during the partnership.

How do I protect my children from a first marriage?

Leave your estate, or your share of the home, on a life interest trust for your spouse. Your spouse has the home for life and the income from the investments, the capital never becomes theirs, and it passes to your children on their death whatever they do in between. The spouse exemption still applies on your death. If the home is owned as joint tenants, the joint tenancy has to be severed first so that your will can deal with your share.

What allowances are available on the second death?

On gov.uk on 22 September 2026, each person has a £325,000 nil rate band and a £175,000 residence nil rate band, and the unused proportion of each transfers from the first death to the survivor's estate. Where the home passes to children, stepchildren or grandchildren, a couple can have up to £1 million before tax on the second death, tapering above a £2 million estate. A life interest trust preserves all of it, and stepchildren count as direct descendants for the residence allowance.

Does divorce cancel my will?

Not the whole will. Section 18A of the Wills Act 1837 treats your former spouse as having died on the date of the divorce, so any gift to them fails and any appointment of them as executor or trustee lapses, and the rest of the will takes effect. Review it anyway, because it may now have no executor, may still benefit your former spouse's family, and says nothing about a new partner. A remarriage after the divorce revokes the will entirely unless it was made in contemplation of that marriage.

Sources & further reading

• Wills Act 1837, section 18
• Wills Act 1837, section 18A
• Inheritance Tax Act 1984, section 49A
• GOV.UK: Inheritance Tax
• GOV.UK: transferring unused residence nil rate band
• GOV.UK: Inheritance Tax nil-rate band and residence nil-rate band from 6 April 2028
• GOV.UK: claim to transfer unused nil rate band (IHT402)
• Inheritance (Provision for Family and Dependants) Act 1975

This article is general information, not legal advice. The law changes and depends on your circumstances — always take advice on your specific situation before acting. Last reviewed 22 September 2026. AD Solicitors Limited is a recognised body regulated by the SRA (no. 8011228).