Inheritance Tax for Unmarried Couples: The Hidden Trap
You have lived together for years. You share a home, finances, and a life. But in the eyes of HMRC, you are strangers — and when one of you dies, the survivor could face an inheritance tax bill of tens or even hundreds of thousands of pounds that a married couple would never pay.
Note: This article uses hypothetical scenarios created for educational purposes only. The names, situations, and outcomes are fictional examples designed to illustrate IHT planning concepts for unmarried couples. Always consult with FCA-regulated financial advisers and qualified tax professionals for advice specific to your circumstances.
Unmarried Couples and IHT: The Key Numbers
The Spousal Exemption Does Not Apply to Unmarried Couples
This is the single most important fact for unmarried couples to understand about inheritance tax. When a married person or civil partner dies, they can leave everything to their spouse completely free of IHT — no limit, no conditions, no tax.
Unmarried couples get none of this. There is no “common-law spouse” recognition in UK tax law, regardless of how long you have been together. Whether you have cohabited for 2 years or 30 years, your partner is treated the same as any unrelated beneficiary.
This means that when an unmarried partner dies and leaves assets to the surviving partner, everything above the nil-rate band of £325,000 is taxed at 40%.
What This Means in Practice
Lisa and Mark have lived together for 15 years. They jointly own a house worth £400,000 (£200,000 each) and have £100,000 in joint savings (£50,000 each). Lisa also has a pension worth £150,000. Mark has no will.
Mark dies suddenly. Without a will, the intestacy rules apply — and under intestacy, unmarried partners inherit nothing. Mark's assets would pass to his nearest blood relatives (parents, siblings, or their children).
Lisa could lose her share of the home entirely. Even if Mark had a will leaving everything to Lisa, the IHT position would be:
| Asset | Value |
|---|---|
| Mark's share of house | £200,000 |
| Mark's share of savings | £50,000 |
| Total estate | £250,000 |
| Less: nil-rate band | −£325,000 |
| Taxable estate | £0 |
| IHT | £0 |
In this case, Mark's estate falls within his nil-rate band, so no IHT is due. But this is only because their assets are relatively modest. For many couples, the picture is very different.
No Transferable Nil-Rate Band for Unmarried Partners
When a married person dies, any unused nil-rate band can be transferred to their surviving spouse. This means a surviving husband or wife can potentially have a combined NRB of up to £650,000, plus up to £350,000 of residence nil-rate band — a total of £1,000,000 tax-free.
Unmarried couples cannot transfer any unused allowance. Each partner has their own £325,000 NRB, and when one dies, any unused portion is simply lost. The survivor has only their own £325,000 to offset against their estate.
| Allowance | Married couple (surviving spouse) | Unmarried couple (surviving partner) |
|---|---|---|
| Own NRB | £325,000 | £325,000 |
| Transferred NRB from deceased | Up to £325,000 | £0 |
| Own RNRB | Up to £175,000 | Up to £175,000* |
| Transferred RNRB from deceased | Up to £175,000 | £0 |
| Maximum tax-free amount | £1,000,000 | £500,000* |
*RNRB only applies if the property passes to direct descendants (children/grandchildren), not to an unmarried partner
The RNRB Position for Unmarried Couples
The residence nil-rate band (RNRB) adds up to £175,000 to the tax-free allowance when a home is left to “direct descendants” — children, grandchildren, or stepchildren. Read our full RNRB guide for details.
For unmarried couples, this creates a complication:
- If you leave your home to your partner, the RNRB does not apply (they are not a direct descendant)
- If you leave your home to your children, the RNRB does apply — but your partner may lose their home
- A trust arrangement can sometimes solve this, allowing your partner to live in the property while it ultimately passes to your children
Case Study: Jake and Sarah
Jake (58) and Sarah (55) have lived together for 12 years. They jointly own a house worth £550,000 and have combined savings of £80,000. Neither has been married before. Jake has two children from a previous relationship. Sarah has no children.
If Sarah dies first and leaves everything to Jake:
| Component | Value |
|---|---|
| Sarah's share of house | £275,000 |
| Sarah's share of savings | £40,000 |
| Sarah's total estate | £315,000 |
| Less: Sarah's NRB | −£325,000 |
| Less: RNRB | £0 (not leaving to direct descendants) |
| Taxable estate | £0 |
| IHT | £0 |
Sarah's estate is just within her NRB, so no IHT is due on the first death. But Sarah's unused NRB cannot be transferred to Jake.
When Jake later dies, his estate includes the entire house (now worth £550,000 assuming no change) plus savings. If Jake leaves the house to his children:
| Component | Value |
|---|---|
| House (now fully Jake's) | £550,000 |
| Savings | £80,000 |
| Jake's total estate | £630,000 |
| Less: Jake's NRB | −£325,000 |
| Less: RNRB (leaving home to children) | −£175,000 |
| Taxable estate | £130,000 |
| IHT at 40% | £52,000 |
Jake's estate faces £52,000 in IHT. If Jake and Sarah had been married, Jake could have claimed Sarah's transferred NRB (£325,000) and transferred RNRB (£175,000), giving him £1,000,000 tax-free — and paying £0 in IHT.
The cost of not being married in this scenario: £52,000.
Six Planning Strategies for Unmarried Couples
1. Write a Will
Without a will, your unmarried partner inherits nothing under intestacy rules. A will is the absolute minimum. It does not reduce IHT, but it ensures your partner actually receives your assets. Consider including a nil-rate band discretionary trust to make the most of your £325,000 allowance.
2. Consider Marriage or Civil Partnership
This is the most effective IHT planning measure for unmarried couples. Marriage or civil partnership gives immediate access to the unlimited spouse exemption and the transferable nil-rate band. For some couples, a simple registry office ceremony could save hundreds of thousands in IHT.
3. Take Out Life Insurance in Trust
A whole-of-life insurance policy written in trust can provide your partner with funds to pay any IHT bill without the proceeds being added to the estate. This is particularly useful if most of your wealth is tied up in property that cannot easily be liquidated.
4. Make Gifts During Your Lifetime
Gifts between unmarried partners are potentially exempt transfers (PETs). If the giver survives seven years, the gift falls outside the estate entirely. Smaller gifts may qualify for annual exemptions.
5. Use the Normal Expenditure from Income Exemption
Regular gifts from surplus income are immediately exempt from IHT with no seven-year wait. If one partner earns significantly more, regular contributions to the other partner's savings could reduce the higher-earning partner's estate over time.
6. Equalise Your Estates
If one partner holds most of the assets, their estate may exceed the NRB while the other partner's estate is well below it. Restructuring ownership so both partners have roughly equal estates means both NRBs are used effectively. This requires careful planning to avoid creating immediate gift/IHT issues.
Frequently Asked Questions
Do unmarried couples pay inheritance tax?
Yes. Unmarried couples do not benefit from the spousal exemption that allows married couples and civil partners to pass assets to each other completely free of inheritance tax. When an unmarried partner dies, everything they leave to their partner is treated the same as a gift to any other individual — and is subject to IHT above the nil-rate band of £325,000.
Is there a common-law spouse exemption for inheritance tax in the UK?
No. There is no such thing as a 'common-law spouse' in UK tax law. No matter how long you have lived together, you do not gain any IHT spousal exemption unless you are legally married or in a registered civil partnership. This is one of the most common and costly misconceptions in estate planning.
How can I protect my partner from inheritance tax if we're not married?
Options include: writing a will that makes best use of the nil-rate band, taking out a whole-of-life insurance policy written in trust to cover the expected IHT bill, making regular gifts from surplus income, considering marriage or civil partnership (which gives immediate access to the spouse exemption), and equalising estates between partners to use both nil-rate bands.
Does a will help with inheritance tax for unmarried couples?
A will determines who receives your assets — it does not change the amount of IHT due. Without a will, unmarried partners may receive nothing at all under intestacy rules. With a will, you can leave assets to your partner, but they will still be subject to IHT above the nil-rate band. A will is essential but is not a substitute for IHT planning.
What is the nil rate band for unmarried couples?
Each person has their own nil-rate band of £325,000, regardless of relationship status. However, unlike married couples, unmarried partners cannot transfer their unused nil-rate band to each other. This means the maximum IHT-free amount available on the first death is £325,000 for an unmarried partner, compared to an unlimited spouse exemption for married couples.
Can unmarried couples transfer their nil rate band?
No. The transferable nil-rate band is only available to married couples and civil partners. When an unmarried partner dies, any unused nil-rate band is lost — it cannot be claimed by the surviving partner. This is one of the key disadvantages of being unmarried for IHT purposes.
Model Your Estate as an Unmarried Couple
Use Estate Map's calculator to see how much IHT your partner could face — and compare the impact of different planning strategies.
Calculate my IHT →This article is for educational purposes only and does not constitute financial advice. Inheritance tax rules for unmarried couples are complex and depend on individual circumstances. Always consult a qualified financial adviser, solicitor, or chartered tax adviser before making estate planning decisions.