Marriage vs cohabitation: The hidden tax differences that couples often overlook

How your relationship status can significantly shape how wealth is taxed and passed on in the UK

When it comes to finances, many couples may assume that simply living together or being married makes little difference to their tax position. Yet in the UK, the legal status of a relationship can have a meaningful impact on Inheritance Tax, Capital Gains Tax and even the way assets are passed on. For some households, this difference only becomes clear at a major life event, when planning opportunities are far harder to recover.

Tax treatment gap couples often miss

Marriage and registered civil partnerships confer a set of tax advantages that cohabiting couples do not automatically receive. One of the most significant is the Inheritance Tax (IHT) spouse exemption, which allows assets to pass between spouses or registered civil partners both during their lifetime and on death, without triggering an immediate IHT charge.

By contrast, unmarried partners do not benefit from this exemption. Instead, assets passing between them on death may be subject to IHT at up to 40% if the estate exceeds the available nil-rate bands. Even jointly owned assets may not fully avoid tax exposure, depending on the ownership structure and the distribution of the estate.

There is also the Marriage Allowance, which allows some couples to transfer a portion of their unused personal allowance if one partner earns below the Income Tax threshold. While the annual benefit is modest, it can still deliver useful savings over time. More broadly, married couples also benefit from Capital Gains Tax (CGT) rules that allow assets to be transferred between spouses on a ‘no gain, no loss’ basis, enabling more efficient long-term tax planning.

Why cohabiting couples can face higher exposure

For unmarried couples, the financial implications often only become apparent during emotionally difficult circumstances, such as illness or bereavement. Unlike married couples, cohabiting partners do not have automatic inheritance rights under intestacy rules in England and Wales, so estates may pass instead to children, parents or other relatives.

This can create unexpected financial pressure at an already stressful time. If a cohabiting partner is not named in a Will, they may need to make a legal claim against the estate, which can be time-consuming and costly. Even when provision is made, Inheritance Tax may still be payable in full, potentially reducing the value of what is passed on.

In some cases, this can lead to forced asset sales, particularly when property is involved, and funds are needed to settle tax liabilities. The absence of spousal exemptions means cohabiting couples often need to rely more heavily on proactive planning tools, such as life insurance written in trust or carefully structured Wills.

Planning ahead can make a significant difference

Understanding how assets are owned and how they will pass on death is essential for all couples, regardless of marital status. For cohabiting partners in particular, joint ownership does not provide the same legal or tax protections as marriage or a registered civil partnership.

For example, pension assets can behave differently depending on the nominated beneficiaries, and not all pension schemes treat unmarried partners equally without clear documentation. Similarly, savings and investments held solely in one partner’s name will not automatically pass to the surviving partner unless there is a valid Will.

Practical planning steps can significantly reduce risk. Writing or updating Wills ensures that assets are distributed according to personal wishes rather than under intestacy rules. In addition, naming pension beneficiaries and placing life insurance policies in trust can help ensure that funds pass efficiently and outside the estate, thereby reducing Inheritance Tax.

Key reliefs available to married couples

Married couples and registered civil partners enjoy several structural tax advantages not available to cohabiting partners. These include unlimited tax-free transfers between spouses during life or on death, which can simplify estate planning and reduce immediate tax exposure.

Another important benefit is the ability to transfer unused Inheritance Tax allowances, including the nil-rate band and the residence nil-rate band, between spouses. This can effectively double the threshold on second death, increasing the amount that can pass to beneficiaries free of IHT.

Capital Gains Tax planning is also more flexible within marriage. Assets can be transferred between spouses without triggering a disposal, enabling couples to manage gains more efficiently across both individuals’ tax allowances. This can be particularly valuable for investment portfolios, second properties or business assets.

Closing the gap through early financial planning

The differences between marriage and cohabitation are not merely legal technicalities; they can have real financial consequences over time. While cohabiting couples may choose not to marry for personal or practical reasons, it remains important to understand the potential tax implications and plan accordingly.

Early financial planning can help bridge many of the gaps. Reviewing Wills, ensuring beneficiary nominations are up to date and assessing Inheritance Tax exposure can significantly improve outcomes. In some cases, couples may also consider formalising arrangements or using trusts and insurance solutions to replicate protections automatically available to married couples.

Taking advice early allows couples to make informed rather than reactive decisions, particularly where property ownership, pensions or blended families are involved.

Ready to take action to protect your position?

If you would like further information on how marriage or cohabitation could affect your tax position, or support with reviewing your financial and estate planning arrangements, please contact us. We can help you understand your options and ensure your plans are structured in a tax-efficient, legally robust way that reflects your personal circumstances and long-term goals.

THIS ARTICLE DOES NOT CONSTITUTE TAX, LEGAL OR FINANCIAL ADVICE AND SHOULD NOT BE RELIED UPON AS SUCH. ESTATE AND TAX PLANNING ARE NOT REGULATED BY THE FINANCIAL CONDUCT AUTHORITY. FOR GUIDANCE, SEEK PROFESSIONAL ADVICE.