Estate planning and wills for blended families in the UK need careful thought. Without a properly structured plan, second spouses and children from previous relationships can end up disinherited, and HMRC can take a far bigger share than necessary through Inheritance Tax (IHT).
This guide focuses on two things: protecting every member of a blended family in your will, and using IHT planning tools (trusts, the residence nil rate band, life insurance, and lifetime gifts) to keep more of your estate inside the family.
- Blended families have competing interests between a new spouse, biological children, and stepchildren. A standard “mirror will” rarely solves this, and intestacy rules certainly do not.
- Wills should be reviewed after marriage, remarriage, the birth or adoption of a child, divorce, the purchase of a home, or any large change in assets such as inheriting money or selling a business.
- Trusts (particularly life interest trusts and discretionary trusts), bloodline planning, and proper use of the £325,000 nil rate band plus the £175,000 residence nil rate band are the main tools blended families use to balance fairness with tax efficiency.
Understanding Blended Families in Estate Planning
A blended family is created when one or both partners bring children from a previous relationship into a new marriage or civil partnership. Office for National Statistics data shows step-families now make up a meaningful share of UK households, and the trend is growing as second marriages become more common.
The legal problem is straightforward: UK intestacy rules and standard wills were designed around a single, lifelong marriage with shared biological children. They were not designed for a household where a husband has two children from a first marriage, his wife has one child from her first marriage, and the couple have a third child together. Without a tailored plan, the law produces results that almost no one in that household actually wants.
Defining a Blended Family
For estate planning purposes, a blended family typically includes any of the following: a second (or later) spouse or civil partner; biological children from a previous relationship; biological children from the current relationship; stepchildren who have not been legally adopted; and, in some cases, long-term stepchildren who were treated as part of the family but never formally adopted.
The legal status of each person matters because the law treats them very differently. A biological or legally adopted child is automatic next of kin. A stepchild is not, no matter how close the relationship. Under intestacy rules, a stepchild inherits nothing from a step-parent unless they have been legally adopted.
Common Challenges
Three issues come up again and again with blended families.
The first is the “second spouse problem”. A husband leaves everything outright to his second wife, expecting her to look after his children from his first marriage. After his death she is free to rewrite her will and leave everything to her own children. His children receive nothing.
The second is the family home. The home is often the largest asset, jointly owned, and lived in by the second spouse. Children from the first marriage may have to wait decades to inherit, or risk forcing a sale.
The third is fairness between children of different ages and stages. A 25-year-old stepchild who is established in their career has very different needs from a 7-year-old biological child. Equal shares are not always fair shares, and “fair” is hard to define without specific instructions in a will or trust.
Outdated wills, mirror wills, and assumptions about what a surviving spouse will do are the most common reasons blended family estates end up in dispute or in court under the Inheritance (Provision for Family and Dependants) Act 1975. Reviewing your inheritance planning and estate plan every few years prevents most of these problems.
Why Regularly Updating Your Estate Plan Is Crucial
A will is a snapshot of your wishes at one moment in time. Lives change, and so do estates. For blended families, the cost of failing to update a will is usually higher than for a traditional family because there are more people with potentially competing interests.
A good rule of thumb is to review your will every three to five years, and immediately after any of these triggers: marriage, civil partnership, divorce, the death of a beneficiary or executor, the birth or adoption of a child, a significant inheritance, the sale of a business, the purchase or sale of a property, or a substantial change in the value of your estate.
Revising Wills After Remarriage
Marriage automatically revokes any earlier will in England and Wales, unless that will was specifically written in contemplation of the marriage. Many people do not realise this. Someone who carefully drafted a will leaving assets to their children from a first marriage, and then remarries without making a new will, has effectively died intestate as far as the law is concerned.
If you remarry, you must make a new will. Otherwise the intestacy rules apply, and as set out below they tend to favour the new spouse over biological children from a previous relationship.
Mirror wills (where each spouse leaves everything to the other, and on the second death to all the children equally) are popular because they are simple, but they are weak protection in a blended family. The survivor can change their will at any time after the first death. A more robust option is mutual wills, where both parties sign a binding agreement not to change their wills after the first death, but these are inflexible and often not the right answer either. A life interest trust (covered below) is usually the better tool.
Addressing Changes in Family Dynamics
Births, deaths, divorces, and estrangements all change who should inherit and how much. A will written when your stepchildren were toddlers may no longer reflect your relationship with them as adults. A guardianship clause for a minor child becomes irrelevant once that child turns 18.
Intestacy rules in England and Wales do not recognise stepchildren or unmarried partners. A stepchild who was raised in the household for 20 years receives nothing under intestacy unless legally adopted. An unmarried partner of 30 years receives nothing. The only way to provide for them is in a valid, up-to-date will.
Key Estate Planning Tools for Blended Families
Trusts and tailored wills are the workhorses of blended family planning. They let you provide for a surviving spouse during their lifetime while still protecting capital for your biological children, and they can be structured to reduce IHT.
Trusts and Life Interest Trusts
A life interest trust (sometimes called an immediate post-death interest trust, or IPDI) is the most common structure for blended families. You leave assets, often the family home or a share of it, into a trust on your death. Your surviving spouse becomes the “life tenant” and has the right to live in the home, or to receive income from invested assets, for the rest of their life. When the surviving spouse dies, the assets pass to your chosen beneficiaries (typically your biological children), not to whoever the surviving spouse leaves their estate to.
This structure has two big advantages. The surviving spouse is housed and supported. Your children’s inheritance is locked in and cannot be redirected. For IHT purposes, the spousal exemption usually applies on the first death, and the trust assets are then taxed as part of the surviving spouse’s estate when they die. Both nil rate bands and (provided the home then passes outright to direct descendants such as children, stepchildren or grandchildren, rather than into another discretionary trust) both residence nil rate bands can usually be used, giving a married couple combined IHT-free allowances of up to £1 million on the second death.
Discretionary Trusts
A discretionary trust gives trustees the power to decide which beneficiaries receive what, and when. The settlor (the person creating the trust) writes a letter of wishes to guide the trustees, but the trustees retain legal flexibility.
This is useful in blended families where needs are uncertain. A trustee can give more to a child going through a divorce, less to a child who has already received help, and nothing to a beneficiary who has fallen into addiction or whose marriage is unstable (so that assets are not lost in their divorce settlement).
Discretionary trusts also offer some protection from creditors and means-tested benefit calculations, although they have their own IHT regime (entry charges, ten-year periodic charges, and exit charges) that needs proper planning.
Protecting Inheritance for Biological Children
The single biggest fear most parents have when remarrying is that their children from a first marriage will be cut out. There are several ways to prevent this.
Using Bloodline Wills
A bloodline will is a will, often combined with a trust, written so that assets ultimately pass to your direct descendants rather than to a surviving spouse’s family or future spouses. The structure ensures that when your wealth eventually leaves your estate, it goes to your bloodline.
Bloodline planning typically uses a life interest trust over the family home and a discretionary or capital-protective trust over investments. The surviving spouse benefits during their lifetime, but cannot redirect the underlying capital. On the second death, the assets pass to your named children and grandchildren.
This is particularly important where the surviving spouse may remarry, where there are children from multiple relationships, or where one side of the family is significantly wealthier than the other.
Balancing Interests with Stepchildren
Bloodline planning protects your biological children, but a good blended family plan also recognises stepchildren you have raised. There are several ways to do this. You can leave specific legacies (a fixed sum or item) to stepchildren in your will. You can include them as discretionary beneficiaries of a family trust. You can use life insurance written in trust to provide for stepchildren outside your main estate, leaving the bulk of the estate to your biological children.
The key is to be explicit. Vague language like “my children” can lead to disputes about whether stepchildren are included. Name everyone individually, and state what each person is to receive.
Ensuring Financial Provision for Surviving Spouse
The surviving spouse needs somewhere to live and enough income to live on. The challenge in a blended family is doing this without permanently transferring assets out of the bloodline.
A life interest trust over the home solves the housing question. Income-producing assets (investments, rental property, savings) can also be put into a life interest trust, with the surviving spouse receiving income but not capital. On the second death, capital passes to the children.
For shorter-term liquidity, life insurance and pension death benefits matter, with important changes coming in April 2027.
Life Insurance Policies
Life insurance pays out quickly and outside the estate if it is written in trust, which means the proceeds reach the beneficiary without waiting for probate and, in most cases, without forming part of the estate for IHT.
In a blended family, life insurance is often used in two ways. A policy on the first spouse’s life, written in trust for the children of the first marriage, gives those children an immediate inheritance on the first death without disturbing the surviving spouse’s standard of living. A policy on the second death, written in trust, provides liquidity to pay any IHT due on the family home so that it does not have to be sold to settle the bill.
A whole-of-life policy is usually more appropriate than term insurance for IHT planning because it pays out whenever death occurs.
Pension Funds
Pensions have been one of the most tax-efficient assets to pass on, but this is changing significantly. From 6 April 2027, most unused defined contribution pension funds and lump-sum death benefits will be brought into the estate for Inheritance Tax purposes, following changes announced in the Autumn Budget 2024 and confirmed in draft legislation.
Until 6 April 2027, unused pension pots can generally be passed to beneficiaries outside the estate for IHT, with the beneficiary paying income tax on withdrawals only if the pension holder died after age 75.
From 6 April 2027, unused defined contribution pots will count towards the value of the estate for IHT, and the pension will be taxed at the same 40% rate as other estate assets above the available nil rate bands. The spousal exemption still applies, so pensions left to a spouse or civil partner remain IHT-free. Death-in-service benefits are also expected to remain outside the estate.
For blended families, the implications are significant. If you currently leave your pension to your children and other estate assets to your spouse, your IHT bill from April 2027 onwards could rise sharply. Reviewing nominations, considering whether to draw the pension during retirement instead of preserving it for inheritance, and modelling the new rules against your overall estate are all worth doing well before the change takes effect. Defined benefit (final salary) pensions paid as ongoing income to a dependant are generally outside the new IHT rules, although the detailed treatment of DB lump-sum death benefits is set out in the draft Finance Bill 2025-26 and should be checked with a pensions adviser.
Avoiding Common Pitfalls in Blended Family Estate Planning
Most blended family estate disputes come from the same handful of mistakes.
Failing to make a new will after remarriage is the most common. Marriage revokes earlier wills. The result is intestacy, and intestacy is rarely what anyone wanted.
Relying on mirror wills is the second. The survivor can change their will the day after the funeral. Children from the first marriage have no enforceable claim against a surviving step-parent’s later changes.
Leaving everything to the second spouse on trust that they will “do the right thing” is the third. Sometimes they do. Often relationships break down after the first death, the surviving spouse remarries, or their own children put pressure on them.
Not using available IHT allowances is the fourth. The nil rate band (£325,000) and residence nil rate band (£175,000) are transferable between spouses, giving a married couple up to £1 million in IHT-free allowances if the family home passes to direct descendants. Both thresholds are frozen until 5 April 2031 (extended at the Autumn Statement 2025), so as house prices and asset values rise, more estates will be drawn into the IHT net by fiscal drag. Failing to plan for this can cost the estate hundreds of thousands of pounds.
Clear Communication
A will written in secret often causes more trouble than the assets it distributes. Telling beneficiaries what to expect, and why, removes most of the surprise factor that drives litigation. This does not mean disclosing every figure, but it does mean explaining the broad structure: “the house is in a trust, your stepmother can live there for life, and on her death it passes to you and your sister.”
Stepchildren in particular benefit from being told that they have been considered, even if their share is smaller than that of biological children. Silence is read as exclusion.
Professional Advice
Blended family estate planning sits at the intersection of family law, trust law, tax law, and pensions. A solicitor draws the will and any trusts. An accountant or tax adviser models the IHT position and the timing of lifetime gifts. A financial adviser handles pension nominations and life insurance written in trust.
A specialist private client team that handles blended families regularly will know which structures are robust against future challenges (such as 1975 Act claims) and which are not. The cost of getting this right is usually a few thousand pounds. The cost of getting it wrong is often six figures plus a family fracture.
How to Handle the Family Home
The family home is the centre of most blended family estate problems because it is illiquid, emotionally loaded, and often the largest asset. The way it is owned matters as much as what your will says.
Joint Tenancies vs. Tenancies in Common
Two or more people can own property in one of two ways in England and Wales.
Joint tenants own the property together as a single unit. On the death of one owner, the property passes automatically to the survivor by the right of survivorship. The will is irrelevant. This is simple and works well for first marriages where both partners want everything to pass to the survivor, but it is the wrong structure for most blended families because it leaves children of the first marriage with no claim on the home.
Tenants in common each own a defined share (often 50/50, but it can be any split). Each share can be left in a will to whomever the owner chooses. This is the structure that supports a life interest trust over a half share of the home, allowing the surviving spouse to remain in residence while the deceased’s share is held for the children. Property inheritance and IHT outcomes both depend on getting this right.
For blended families, holding the home as tenants in common is usually the starting point.
Severance of Joint Tenancies
If the home is currently held as joint tenants and you want to switch to tenants in common, the process is called severance. It involves serving a written notice of severance on the other owner and registering the change at HM Land Registry. It can be done unilaterally and does not require the other owner’s consent.
Severance is a simple and inexpensive step, but it has to be done during your lifetime. After death it is too late: the survivorship rule will already have transferred the property automatically to the surviving joint tenant.
For blended families, severing the joint tenancy and putting a life interest trust in place over the deceased owner’s share is one of the most reliable ways to protect both the second spouse and the children of the first marriage.
Legal Considerations and Intestacy Rules
Knowing what the law does in the absence of a will is the best argument for making one. The intestacy rules in England and Wales were not written with blended families in mind, and the results are often the opposite of what the deceased would have chosen.
A will made before remarriage is automatically revoked by that marriage unless it was specifically drafted in contemplation of the marriage. The Court can in some cases admit a partially valid earlier document, but this is uncertain and expensive territory.
Impact of Intestacy Rules
Under the intestacy rules in England and Wales (updated by the Administration of Estates Act 1925 (Fixed Net Sum) Order 2023), where a person dies without a will leaving a spouse or civil partner and children, the estate is divided as follows. The surviving spouse receives all personal possessions, the first £322,000 of the estate (the “statutory legacy”), and half of anything above that figure. The children share the other half of anything above £322,000 equally between them.
In a blended family, “the children” means only the deceased’s biological or legally adopted children. Stepchildren receive nothing. If the entire estate is worth less than £322,000, the surviving spouse takes the lot, and the deceased’s biological children inherit nothing.
If the deceased leaves a spouse but no children, the spouse inherits everything. If there is no spouse, the estate is divided equally between the children, and stepchildren still receive nothing.
Unmarried partners inherit nothing under the intestacy rules, regardless of how long the relationship lasted. They may have a claim under the Inheritance (Provision for Family and Dependants) Act 1975, but this is litigation, not entitlement.
The thresholds and the rules are different in Scotland and Northern Ireland.
Preventing Will Challenges
Even with a valid will, certain people can challenge it under the 1975 Act if they believe reasonable financial provision has not been made for them. Spouses, civil partners, former spouses who have not remarried, children, stepchildren who were treated as children of the family, and anyone who was being financially maintained by the deceased can all potentially bring a claim.
Mirror wills are particularly vulnerable because the surviving spouse can change them. Mutual wills create a binding contract not to change the will, but they are inflexible and can have unintended tax consequences. A properly structured trust, combined with a clear letter of wishes and adult conversations with the family, is usually a more durable answer.
The most effective protection against challenges is a will that is recently dated, clearly drafted, signed and witnessed correctly, and that demonstrably provides for everyone with a reasonable claim, even if not equally.
Summary
Estate planning for blended families is more involved than for a typical first marriage, but the tools are well established. The combination of an up-to-date will, the right ownership structure for the family home (usually tenants in common), a life interest trust to balance the needs of the surviving spouse against the inheritance of biological children, full use of the £325,000 nil rate band and £175,000 residence nil rate band (and their transferable elements), life insurance written in trust, and careful pension planning ahead of the April 2027 IHT changes, will solve the vast majority of blended family planning problems.
The two non-negotiables are these: review your will and your pension nominations whenever your family or your finances change, and take advice from professionals who handle blended family estates regularly. Done properly, the result is a plan that protects everyone you care about and minimises the share that goes to HMRC.
What are the red flags for blended families?
The estate planning red flags are: an out-of-date will (or no will), a will written before remarriage, a family home held as joint tenants when it should be tenants in common, mirror wills with no protection for children of a first marriage, pension nominations that have not been reviewed since the 2024 Budget changes, and an estate large enough to pay IHT but with no plan to use both spouses’ nil rate bands or the residence nil rate band.
Why is it important to update my estate plan after remarriage?
Marriage automatically revokes any will made before it (unless the will was made in contemplation of that specific marriage). Without a new will, the intestacy rules apply, and they will usually leave most or all of the estate to the new spouse, often disinheriting children from a previous relationship. A new will is the only way to make sure both your new spouse and your existing children are provided for.
What are bloodline wills, and how do they protect my biological children?
A bloodline will is a will, often paired with a life interest trust, that ensures assets ultimately pass to your direct descendants rather than to a surviving spouse’s family or to anyone the surviving spouse remarries. The surviving spouse is provided for during their lifetime, but the underlying capital is reserved for your children and grandchildren.
How can life insurance policies benefit my surviving spouse?
A life insurance policy written in trust pays out quickly, outside probate, and usually outside the estate for IHT. In a blended family, this can give the surviving spouse immediate funds to cover bills and living expenses while the rest of the estate is administered. It can also provide liquidity to pay any IHT due, which is particularly useful when the main asset is a family home that nobody wants to sell.
What is the difference between joint tenancies and tenancies in common?
Joint tenants own a property together as a single unit, and on the death of one owner the whole property passes automatically to the survivor regardless of what the will says. Tenants in common each own a defined share, and each share can be left by will to whomever the owner chooses. Blended families almost always need tenants in common so that a deceased owner’s share can be put into a trust for their children rather than passing automatically to the second spouse.
How does the residence nil rate band help blended family estates?
The residence nil rate band (RNRB) gives up to £175,000 of additional IHT-free allowance per person where the family home (or its value) passes to “direct descendants”, which includes biological children, adopted children, foster children, stepchildren, and grandchildren. It is transferable between spouses, so a married couple can pass on up to £1 million IHT-free if both nil rate bands and both residence nil rate bands are available and the home goes to qualifying descendants. The thresholds are frozen until 5 April 2031.
For blended families, the inclusion of stepchildren in the definition of “direct descendant” is a significant planning point. There is one trap to be aware of: if the home is left into a discretionary trust on death, the RNRB is not available, even if the only beneficiaries are direct descendants. An immediate post-death interest (IPDI) trust giving a surviving spouse a life interest, with the home then passing outright to direct descendants on the second death, generally does qualify, which is why this structure is so widely used in blended family planning.