Blended families and unmarried partners: who actually inherits, and how a will fixes it

The two relationships the intestacy rules cannot see

Die without a will in England and Wales and a fixed statutory formula decides who gets everything you own. That formula recognises exactly four kinds of connection: marriage, civil partnership, blood, and legal adoption. A stepchild you raised from toddlerhood is not on the list. Neither is a partner you have lived with, bought a house with and raised children with for twenty years. Under the intestacy rules, both receive precisely nothing.

This page is for blended families and cohabiting couples who want to fix that with a properly drafted will. It covers what the default rules actually do to a second-marriage estate, why the "common-law spouse" idea is a myth, and the specific drafting tools, life interest trusts, property protection trusts and tenancy changes, that let you look after a current partner and children from an earlier relationship at the same time. If you want the underlying default rules in full, our companion guides on who inherits when there is no will and intestacy and unmarried partners cover those; this article is about the will that stops the defaults applying to you. Everything here is general information to help you prepare, not legal or financial advice for your specific situation.

What the default rules do to a blended family

The order of entitlement is set by law and you can check any scenario with the official GOV.UK intestacy tool. Where the person who died leaves a spouse or civil partner and children, the spouse takes the personal possessions, a fixed statutory legacy of £322,000 (the figure for deaths on or after 26 July 2023, per HMRC's Inheritance Tax Manual at IHTM12122), and half of whatever remains. The children share the other half of the remainder, but only children the law recognises: birth children and legally adopted children. Here is how the main relationships in a blended household come out:

Relationship to the deceased	Automatic entitlement under intestacy
Spouse or civil partner (including a recent second marriage)	Personal possessions + first £322,000 + half the rest
Birth children (from any relationship)	Equal shares of the other half above £322,000
Legally adopted children	Same as birth children
Stepchildren (never adopted)	Nothing
Unmarried partner (any length of relationship)	Nothing
An ex-spouse you divorced	Nothing

Notice the asymmetry that catches second marriages. A spouse of eighteen months has a powerful statutory entitlement. A stepdaughter of thirty years has none. And because so many second-marriage estates are worth less than £322,000 once the house is shared or mortgaged, the "half of the rest" for the children is frequently half of nothing.

A worked example: Dev's £610,000 estate

Dev, 58, owns a house worth £400,000 in his sole name and has £210,000 in savings and investments, a £610,000 estate. He has two adult children, Priya and Arun, from his first marriage, and a stepson, Callum, whom he has raised since Callum was six. Dev remarried nine years ago; his second wife is Sandra, Callum's mother. Dev never got round to making a will after the wedding (and any earlier will was revoked by the marriage anyway, a rule confirmed in GOV.UK's guidance on updating your will).

On Dev's death intestate, the estate divides like this:

• Sandra: personal possessions, the £322,000 statutory legacy, and half of the remaining £288,000, which is £144,000. Total: £466,000 plus the contents.
• Priya and Arun: the other £144,000, so £72,000 each.
• Callum: £0. He was never adopted, so the rules do not see him.

Two small changes in the facts swing the outcome wildly. If Dev and Sandra had never married, Sandra would receive nothing at all and the children Priya and Arun would take the entire £610,000 (Callum still gets nothing). And if the estate had been £300,000 rather than £610,000, Sandra would take all of it and Dev's own children would receive nothing. None of these outcomes is what most people in Dev's position would choose, which is rather the point: intestacy is a formula, not a judgment about your family.

The common-law marriage myth

Surveys have repeatedly found that a large share of cohabiting adults in the UK believe that living together long enough creates a "common-law marriage" with inheritance rights. It does not, and it has not for centuries. In England and Wales there is no length of cohabitation, no shared mortgage, no joint children, that gives a surviving partner an automatic share of an estate under intestacy. The GOV.UK checker asks first whether the deceased had a surviving husband, wife or civil partner; answer no, and a partner never features again.

The one safety net is the Inheritance (Provision for Family and Dependants) Act 1975. A partner who lived with the deceased as if married for the whole of the two years before the death, or who was financially maintained by them, can apply to court for reasonable financial provision from the estate (the Act's text is on legislation.gov.uk). Treat that as the fire escape, not the front door. It is a court claim brought against the very relatives who inherited instead, it is usually limited to what the claimant needs for maintenance rather than a fair share, and it must generally be started within six months of the grant of probate. Our guide to Inheritance Act 1975 claims explains the route in more detail; anyone actually facing this situation needs a contentious probate solicitor, not a template letter.

Sideways disinheritance: the second-marriage failure mode

Even couples who do make wills often set up the classic trap. Each leaves everything to the other, with the children to inherit on the second death. The problem is what happens between the two deaths. Once the survivor owns everything outright, they can make a new will leaving it all to their own children, or to a new partner. Remarriage revokes their existing will automatically, so a widowed spouse who remarries may put the whole combined estate onto a fresh intestacy that favours the new husband or wife. The first person to die intended their share to reach their own children eventually; instead it slid sideways into another family. Estate planners call this sideways disinheritance, and blended families are its natural habitat.

Mirror wills do not solve it, because a mirror will is just a matching will that either person remains free to change. What solves it is drafting that fixes the destination of your share at your death, while still looking after your partner for life.

The will structures that actually protect both sides

1. A life interest (property protection) trust over your share of the home

The couple first sever any joint tenancy so they own the home as tenants in common, each with a defined share. Each will then leaves that share to a trust under which the survivor has a life interest: the right to live in the property for the rest of their life, and usually to move house with the trust following the sale proceeds. Only when the survivor dies (or, if the will says so, remarries or moves into long-term care) does the share pass to the final beneficiaries the first person chose, typically their own children. The survivor is never uprooted; the children's inheritance is never at the survivor's discretion. Our dedicated guide to the property protection trust in a will walks through the mechanics, costs and inheritance tax treatment.

2. Naming stepchildren and partners explicitly

Because the default rules give them nothing, a stepchild or unmarried partner only inherits if your will says so, by name or by a carefully drafted class gift. A will that leaves shares to "my children" will normally be read as birth and adopted children only, so a family that thinks of three children as simply "the kids" can accidentally exclude one of them. If you intend stepchildren to take equally, the will should say so in terms.

3. Getting the tax allowances your family is entitled to

Here succession law and tax law point in opposite directions, usefully. For the residence nil-rate band, the extra allowance of up to £175,000 where a home passes to direct descendants, GOV.UK's RNRB guidance counts stepchildren as direct descendants. So a will leaving the home (or a share of it) to a stepchild can qualify for the same allowance as a gift to a birth child; intestacy, which gives the stepchild nothing, wastes it. Unmarried partners face the harsher tax edge: there is no spouse exemption between cohabitants, so anything you leave a partner above your available allowances is taxed at 40%. The interaction with the £325,000 nil-rate band and transferable allowances is covered in our guide to the married couple's threshold and the RNRB, and it is one more reason cohabiting couples in particular need deliberate planning rather than defaults.

4. Reviewing after every marriage, divorce or new arrival

Marriage or civil partnership revokes an existing will unless it was expressly made in contemplation of that marriage. Divorce does not revoke a will but treats the former spouse as having died before you for the purposes of gifts and executorship. Any of these events in a blended family should trigger an immediate review; GOV.UK suggests revisiting a will every five years and after any major life change. Work through our making a will checklist to see what your current arrangements cover and where the gaps sit, and see the wider wills pillar guide for the signing and witnessing formalities that make the document valid.

Getting it done

Blended-family wills are precisely the situation where a cheap template underperforms: severing a tenancy, drafting a life interest, balancing a new spouse against first-marriage children and defining exactly who counts as a child are drafting decisions with decades of consequences. A qualified will writer or solicitor who handles trust-based wills can usually structure all of it in a single engagement, and our blended families hub gathers the rest of our guidance for step-parents, second marriages and cohabiting couples. If you take one thing from this page, take this: for the two people the intestacy rules cannot see, your will is not a formality, it is the only document standing between them and nothing.