The mirror-will trap
A mirror will is not a contract, and nothing stops your spouse rewriting theirs the day after your funeral. Most couples in a second marriage make “mirror wills”: each leaves everything to the other, then — if the other has already died — to “our children” or “my children”. It reads like a shared plan. Legally, it is two entirely separate, independent wills that happen to say similar things.
Each will can be changed by the person who made it, at any time, without telling the other. That is true while you are both alive, and it is just as true of the survivor once the first of you has died. Nothing agreed between the two of you — however clearly, however often repeated — changes that. A will is revocable by its maker until the moment they die, and a mirror will is no exception.
Two wills, not one plan
Each spouse’s will can be revoked or rewritten by that spouse alone. A shared understanding, even one written down informally, is not the will — it is a hope about what the survivor will choose to do.
Your children have no fallback
If your spouse remarries, falls out with your children, or simply changes their mind, your children have no legal entitlement to anything from your spouse’s estate — even assets that came from your side of the marriage — unless your spouse chooses to include them.
The two traps compound each other. A mirror will not binding the survivor is one problem. §2 covers the other: remarriage itself can wipe the will out before that question ever arises.
Marriage cancels your old will
If you remarry, your existing will is automatically cancelled — even one that carefully provided for children from an earlier relationship. s.18 Wills Act 1837, as substituted by the Administration of Justice Act 1982, provides that a will “shall be revoked by the testator's marriage”. It makes no exception for a will that already named your children. Divorce changes your legal position too, but only in a narrower way — remarriage wipes the will out entirely.
The narrow exception
s.18 Wills Act 1837 makes one exception: a will survives your marriage if it shows you were “expecting to be married to a particular person” and that you intended the will not to be revoked by it — the exception is narrow, because it has to name or clearly identify that particular person, not a general hope of marrying someone eventually.
Most wills people already have were never drafted with this wording, because they were made before remarriage was on the horizon at all.
The full rules, including the power-of-appointment and civil-partnership-conversion exceptions, are set out in full on Valoren’s dedicated marriage-and-wills page — this page deliberately doesn’t repeat them.
Under review, not yet changed (as of 30 August 2026): the Law Commission’s May 2025 report on wills law, Modernising Wills Law, recommends scrapping revocation-on-marriage altogether — partly to close this exact route to so-called “predatory marriage” — and has published a draft Wills Bill to do it.
Nothing has changed yet: s.18 Wills Act 1837 remains in force today, and everything above describes the law as it currently stands.
This is the specific trap for blended families. Someone makes a will after a divorce or bereavement, naming their own children carefully. Years later they remarry, and never think to make a new will — because as far as they know, they already have one. If they die before redoing it, that earlier will has already been revoked, and they die intestate.
The intestacy rules then apply based on the new spouse, not on whatever the revoked will tried to arrange. §3 covers exactly what that means for a blended family.
Intestacy is unkind to blended families
Die without a will, and your spouse’s statutory share comes off the top before your children see anything. Since s.1 ITPA 2014 took effect on 1 October 2014, a surviving spouse or civil partner who inherits alongside the deceased’s children takes, absolutely: all personal chattels; a fixed statutory legacy; and half of whatever remains. The children share the other half, held on statutory trusts until they turn 18. Citizens Advice sets out the same rule in plain English: who can inherit if there’s no will.
The statutory legacy is currently £322,000, in force for deaths on or after 26 July 2023 (uprated from £270,000 by SI 2023/758 — The Administration of Estates Act 1925 (Fixed Net Sum) Order 2023 — see HMRC’s IHTM12122 for the full historical table).
The figure is reviewed periodically by the Lord Chancellor and will move again — check the current figure before relying on it for a specific estate.
Take an estate (setting personal belongings aside) worth £600,000. The spouse takes the first £322,000, then half of the remaining £278,000 — £139,000 — outright. That is £461,000 to the spouse, roughly three-quarters of the estate. The children divide the remaining £139,000 between them.
If the estate is worth £322,000 or less, the spouse takes all of it and the children receive nothing under intestacy at all.
The half-share is only ever available if you die first, leaving a surviving spouse. If your spouse has already died before you, there is no one to split with, and your children simply inherit everything. That single fact governs the split — it doesn’t mean children see nothing under intestacy when you die first: as the example above shows, they take nothing only when the estate is at or below the statutory legacy figure.
The one exception worth knowing
A stepchild genuinely “treated as a child of the family” by the stepparent — s.1 IPFDA 1975 — can apply to court for reasonable financial provision under the Inheritance (Provision for Family and Dependants) Act 1975, even without adoption. This is not an automatic intestacy share: it is a court application, judged on what they need for maintenance rather than a fixed fraction, and it must normally be made within 6 months of the grant of representation (s.4 IPFDA 1975) — a matter for a solicitor, not something to rely on instead of a will.
This page stops at the spouse-and-children split. The full intestacy order — what happens with no spouse, no children, or neither — is covered in full on Valoren’s intestacy page, which already states the same rule this page relies on: stepchildren don’t inherit unless legally adopted.
Two real protections, and their trade-offs
A life interest trust and a mutual wills contract both survive your death — everything in §1 and §2 does not. Both work by taking the decision out of the survivor’s hands rather than trusting them to honour it. They do it in very different ways, with very different costs to the survivor’s own freedom.
A life interest trust
Set up through your will, this gives your spouse a right to income from, or to live in, a specific asset — usually the family home — for the rest of their life, without ever owning it outright. Because they never own the capital, they cannot leave it by their own will: it passes automatically to your children when your spouse dies. For inheritance tax, HMRC treats this as an immediate post-death interest — the first transfer to your spouse keeps full spousal exemption, and the underlying asset counts as part of your spouse’s estate when they die, even though your children actually receive it. The tax mechanics deserve their own full treatment — see the full IPDI breakdown — this is the shape of what it does.
Mutual wills — rare, and worth knowing why
Two people sign mirror-image wills plus a binding agreement not to change them after the first death. Once the first person dies, the agreement locks the survivor in — a court will enforce it against their later will, whatever changes afterwards: a new relationship, a falling-out with a beneficiary, or simply a change of mind. The cost is real: it permanently removes the survivor's own testamentary freedom for the rest of their life. One contentious-probate firm’s own published verdict: mutual wills are “generally inadvisable” for most couples, precisely because of this rigidity.
The difference between the two is what happens to your spouse's own freedom, not just your children's protection. A life interest trust protects your children without permanently freezing your spouse’s ability to respond to their own life afterwards — a new relationship, changed care needs, their own tax planning. A mutual wills agreement protects your children by removing that freedom altogether instead.
Neither is something a template can safely draft: a life interest trust needs the right wording to get the tax treatment, and a mutual wills agreement needs clear evidence that a binding agreement was actually made — identical wills are evidence that an agreement existed (Re Cleaver [1981] 1 WLR 939), but they are not enough on their own: the court must still be satisfied on the balance of probabilities that a binding agreement was actually made, and that agreement may be oral or written (Charles v Fraser [2010] EWHC 2154 (Ch)).
Writing it down at the time is strongly advisable evidentially, even though the law’s actual requirement is proof of the agreement, not a fixed paperwork formality. Both are jobs for a solicitor.
Closing the gap while you can
Everything above is downstream of decisions you can still make. None of this requires an unusual amount of paperwork — it requires the right paperwork, done once, properly.
A will that names both families explicitly
Not a mirror will assuming your spouse will “do the right thing” — a will that decides, in your own document, what happens to your own assets and names your own children as beneficiaries of whatever you choose to protect for them.
Check whether remarriage already revoked yours
If you have married since you last made a will — including one that named your children from before — assume it was cancelled unless it says otherwise. Confirm the exceptions before assuming either way.
Decide the mechanism with proper advice
A life interest trust needs correct drafting to get the IPDI tax treatment; a mutual wills agreement needs clear evidence that a binding agreement was actually made, ideally in writing at the time. Both are jobs for a solicitor, not a template.
Check how the house is held
Joint tenants means the whole property passes automatically to the survivor, overriding anything your will tries to say about your own share. A Form A restriction on the register usually signals tenants in common instead — but its absence isn’t conclusive: a severance by notice isn’t always reflected on the register, and unregistered land has no register to check at all. For a blended family, this decision can matter as much as the will itself.
This is precisely the kind of situation Valoren's wills product is built to catch, not paper over. The free eligibility check runs the same rules a practising solicitor signed off. If it flags a life interest trust or a mutual wills situation, that’s exactly what it’s designed to catch — you’re routed to a specialist with your answers already prepared, rather than sold a simple will that wouldn’t actually protect anyone. Start with the free check.
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Scoped to England and Wales. Checked against legislation.gov.uk, HMRC's Inheritance Tax Manual and Citizens Advice on 30 August 2026. This page explains how the rules work in general — it is not advice on your own situation. For a will, a trust, or a mutual wills agreement, take advice from a solicitor.
Three ways to take this further, depending where you are.
If you already have a will, the first question is whether it still counts. If you don’t, the intestacy rules are already deciding this for you, right now, whether or not you’ve thought about it.
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A free eligibility check that flags exactly this kind of complexity and routes you to a specialist, with your answers already prepared.
See the wills door→Already remarried?Does marriage revoke a will?
The s.18 trap in full: exceptions, timing, and exactly what to check today.
Read the full rules→No will at all?What happens if you die without a will
The full intestacy order for England and Wales, beyond the spouse-and-children split covered here.
See the full order→