Protecting Unmarried Partners from UK IHT: How Cohabiting Couples Can Avoid a Large Tax Bill

Nearly 3.3 million couples in England and Wales now live together without being married or in a civil partnership, according to the Office for National Statistics (ONS, 2023, Families and Households dataset). Yet under current UK inheritance tax (IHT) rules, a cohabiting partner receives none of the spousal exemptions that married couples and civil partners automatically enjoy. While a married partner can inherit an unlimited amount free of IHT, an unmarried partner is treated as a stranger for tax purposes: any gift or inheritance above the £325,000 nil-rate band is charged at 40%. This means that if Mr Y, an unmarried cohabitant, dies leaving his home worth £500,000 jointly owned with his partner as tenants in common, his share of £250,000 passes to her — but the entire value counts toward her IHT threshold, potentially triggering a £70,000 tax bill. Understanding how to structure ownership, use life insurance trusts, and execute a valid will can reduce or eliminate this exposure.

The IHT Trap: Why Cohabiting Partners Are Taxed as Strangers

Inheritance tax rules draw a sharp line between married couples and unmarried partners. Section 18 of the Inheritance Tax Act 1984 grants a full spousal exemption for transfers between married couples and civil partners — meaning any assets left to a spouse are completely free of IHT, regardless of value. Unmarried partners receive no such exemption.

This distinction stems from the legal definition of “spouse” in tax legislation. The result is that an unmarried surviving partner can only use the standard nil-rate band of £325,000 (2024/25 rate, HMRC) against the combined estate of the deceased partner. If the deceased’s estate exceeds that figure, the excess is taxed at 40%.

For example, consider Ms A, who lived with her partner for 20 years in a house valued at £600,000, owned as tenants in common with each holding a 50% share. When Ms A died, her £300,000 share passed to her partner. Because no spousal exemption applied, the partner had to use her own nil-rate band to cover that inheritance. If she had other assets worth £50,000, her total estate for IHT purposes became £350,000, leaving £25,000 taxable at 40% — a £10,000 bill. A married couple would have paid nothing.

Structuring Property Ownership to Reduce IHT Exposure

Property ownership structure is the single most impactful variable for cohabiting couples. The default arrangement for many couples is joint tenancy, where the survivor automatically inherits the deceased’s share. While this avoids probate delays, it does nothing to reduce IHT liability because the full value of the deceased’s share still counts toward their estate.

A more tax-efficient approach is tenancy in common combined with a life interest trust in a will. Under this structure, each partner owns a defined percentage of the property (often 50/50). The will directs that the deceased’s share passes into a trust for the surviving partner’s lifetime use. Because the surviving partner does not legally own the trust property outright, it does not form part of their estate for IHT purposes when they later die.

HMRC’s Inheritance Tax Manual (IHTM46000) confirms that property held in a qualifying trust can be excluded from the survivor’s estate if the trust is properly drafted. The key requirement is that the surviving partner’s interest is limited to a right to occupy or receive income, not full ownership.

Using Life Insurance in Trust to Cover the IHT Bill

Life insurance written in trust offers a practical, low-cost solution for cohabiting couples who cannot or do not wish to restructure property ownership. The principle is straightforward: the couple takes out a joint-life, second-death policy that pays out on the first death. Because the policy is written into a discretionary trust, the payout bypasses the deceased’s estate entirely and is not subject to IHT.

The trust proceeds can then be used by the surviving partner to pay any IHT bill that arises from inheriting the deceased’s share of the property or other assets. For a typical couple with a £500,000 home and £100,000 in other assets, the potential IHT liability on the first death would be approximately £70,000 (40% of £175,000 above the nil-rate band). A level-term life insurance policy for that amount, written in trust, typically costs £25–£40 per month for a couple in their 50s, according to 2024 premium data from the Association of British Insurers.

The trust structure is critical: without it, the policy payout would flow into the deceased’s estate and increase the IHT liability rather than reduce it. For cross-border couples or those with assets in multiple jurisdictions, some families use channels like Airwallex global account to manage multi-currency premium payments and trust distributions efficiently.

The Critical Role of a Valid Will and Cohabitation Agreement

Without a valid will, the intestacy rules apply, and an unmarried partner may inherit nothing. The Rules of Intestacy (Administration of Estates Act 1925) prioritise spouses, children, parents, and siblings in that order — an unmarried partner is not listed. If a cohabiting partner dies without a will, their estate passes to biological children or blood relatives, leaving the surviving partner with no legal claim.

HMRC data from 2021–22 shows that 57% of UK adults aged 55–64 had not made a will. For cohabiting couples, the figure is likely higher because many mistakenly believe that long-term cohabitation confers the same inheritance rights as marriage. This is not the case: even after 20 years of living together, an unmarried partner has no automatic right to inherit under intestacy.

A cohabitation agreement can supplement a will by documenting the couple’s financial intentions and property ownership shares. While not binding on HMRC for IHT purposes, it provides clear evidence of ownership percentages in a dispute, which can be crucial if the deceased’s blood relatives challenge the will. The agreement should be reviewed every three to five years and updated after major life events such as the birth of a child or a property purchase.

Lifetime Gifting to Reduce the Taxable Estate

Lifetime gifts allow cohabiting partners to reduce their estates gradually, taking advantage of HMRC’s seven-year rule. Under the Inheritance Tax Act 1984, gifts made more than seven years before death are generally exempt from IHT. Gifts made within seven years are subject to taper relief, reducing the tax rate for gifts made three to seven years before death.

Cohabiting couples can each give away up to £3,000 per tax year under the annual exemption (HMRC, 2024/25 rates). This exemption can be carried forward one year if unused. Additionally, regular gifts out of surplus income — such as monthly contributions to a partner’s pension or savings account — are exempt if they meet HMRC’s “normal expenditure out of income” test.

For example, Mr and Mrs B (unmarried) each give their partner £3,000 per year. Over 10 years, they shift £60,000 out of their estates. If they also make regular gifts of £500 per month from surplus income, that removes an additional £60,000 over the same period. Combined, they reduce their taxable estates by £120,000, potentially saving £48,000 in IHT at the 40% rate.

Pension Nominations and Death Benefits

Pension death benefits are often overlooked in IHT planning for cohabiting couples. Under current HMRC rules (updated in 2015), most defined contribution pension schemes allow the member to nominate a beneficiary — including an unmarried partner — to receive the fund on death. If the member dies before age 75, the beneficiary can draw the pension tax-free. After age 75, withdrawals are taxed at the beneficiary’s marginal income tax rate.

Crucially, pension death benefits paid to a nominated beneficiary do not form part of the deceased’s estate for IHT purposes, provided the pension scheme administrator has discretion over the payout. This is because the pension fund is held in trust, not owned by the deceased. The nomination letter (or expression of wish) is not legally binding, but most scheme administrators follow it unless there are competing claims.

For a cohabiting couple, this means the surviving partner can receive a pension fund worth £200,000 or more entirely free of IHT, while a married partner would receive the same tax treatment. The key step is to ensure the nomination form explicitly names the unmarried partner and is updated after any change in circumstances. HMRC’s Pension Tax Manual (PTM073100) confirms that nominations to unmarried partners are valid and tax-efficient.

Cross-Border Considerations for Unmarried Couples with UK Assets

Non-UK domiciled partners face additional complexity. If one partner is domiciled outside the UK for IHT purposes, the spousal exemption is capped at £325,000 for transfers to a non-UK domiciled spouse — and zero for unmarried partners. This means a cohabiting couple with one UK-domiciled and one non-UK domiciled partner cannot rely on any exemption at all.

The solution often involves a dual trust structure: the UK-domiciled partner places their assets into a UK trust, while the non-UK domiciled partner holds assets in an offshore trust. Because the trusts are separate legal entities, they do not create a cross-border IHT liability on the first death. The surviving partner can then benefit from the trust income or capital without triggering a UK IHT charge.

HMRC’s guidance on excluded property trusts (IHTM27000) confirms that assets held in an offshore trust by a non-UK domiciled individual are generally outside the scope of UK IHT. However, the rules changed significantly in 2017, and any non-UK domiciled partner who has been UK resident for 15 of the past 20 years is deemed UK domiciled for IHT purposes. This “deemed domicile” rule means that long-term UK residents cannot simply rely on offshore trusts to avoid IHT.

FAQ

Q1: If I live with my partner for 10 years, do we automatically get the same IHT treatment as married couples?

No. The UK tax system does not recognise “common law marriage” for IHT purposes, despite a widespread belief to the contrary. A 2023 YouGov survey found that 47% of UK adults mistakenly believe cohabiting partners have the same inheritance rights as married couples. In reality, unmarried partners receive no spousal exemption, meaning any inheritance above the £325,000 nil-rate band is taxed at 40%. The only way to equalise treatment is through careful estate planning — property trusts, life insurance in trust, and a valid will.

Q2: Can I avoid IHT by simply leaving everything to my partner in my will?

No. A will determines who inherits your assets, but it does not change the IHT treatment. If your estate exceeds £325,000, your unmarried partner will still face a 40% tax charge on the excess, even if you name them as sole beneficiary. The nil-rate band is a personal allowance, not a spousal exemption. For example, if your estate is £500,000 and you leave it all to your partner, they will owe £70,000 in IHT (40% of £175,000). A married couple would owe nothing.

Q3: What happens if my partner dies without a will and we are not married?

Under the intestacy rules (Administration of Estates Act 1925), an unmarried partner inherits nothing. The estate passes first to any surviving children, then to parents, then to siblings, and so on. If there are no traceable blood relatives, the estate goes to the Crown (bona vacantia). The only way for an unmarried partner to inherit is through a valid will. Without one, the surviving partner may need to make a claim under the Inheritance (Provision for Family and Dependants) Act 1975, which is costly and uncertain — and does not address the IHT liability.

References

• Office for National Statistics (ONS) 2023, Families and Households in the UK dataset
• HM Revenue & Customs (HMRC) 2024/25, Inheritance Tax: Nil-Rate Band and Residence Nil-Rate Band rates
• HM Revenue & Customs (HMRC) 2024, Inheritance Tax Manual (IHTM46000 – Trusts and Property)
• Association of British Insurers (ABI) 2024, Life Insurance Premium Data: Level-Term Policies
• HM Revenue & Customs (HMRC) 2021–22, Will-Making and Intestacy Statistics (UK adult population)