Cohabitation by age
Cohabitation is now the majority living arrangement for coupled adults in their late twenties. Among people aged 25 to 29 in England and Wales, the share of those in a couple who were cohabiting rather than married rose from 56.5% in 2011 to 71.6% in 2021 (ONS, Census 2021). The ONS reports the increase held across all age groups under 85.
Why age matters here. Younger cohabiting couples often buy property together, have children, and build joint finances long before, or instead of, marrying. Because the intestacy rules give a surviving cohabitant no automatic entitlement (
gov.uk, intestacy rules, as at July 2026), the gap between how couples live and what the law assumes can widen with each cohort. This is general information, not advice.
Cohabiting versus married and lone-parent families
Cohabiting couples remain a minority of all UK families, though a growing one. Married couple families were still the largest group in 2023 at 12.7 million (65% of families), with lone-parent families at 3.2 million (16%) and cohabiting couple families at 3.5 million (18%), per the ONS (ONS, Families and households in the UK: 2023).
| Family type (UK) | Number (2023) | Share of families |
|---|
| Married couple families | 12.7 million | 65% |
| Cohabiting couple families | 3.5 million | 18% |
| Lone-parent families | 3.2 million | 16% |
| Civil partner couple families | 198,000 | 1% |
Source: ONS, Families and households in the UK: 2023 (reference year 2023). Percentages are rounded by the ONS and may not sum to 100.
What the numbers mean
The headline story is a widening gap between how couples live and what the law provides. Cohabitation has more than doubled in three decades to over 3.5 million couples (gov.uk, 2025), yet the legal framework for unmarried partners has changed little. In our experience, that mismatch is where problems tend to surface.
A recurring theme in the official data is the persistence of the "common law marriage" belief: the government's 2025 consultation reports that 47% of people in England and Wales think such a status exists (gov.uk, A fairer end to relationships). It does not. A cohabiting partner has no automatic right to inherit under the intestacy rules, however long the relationship (gov.uk, intestacy rules, as at July 2026).
Cohabiting couples are now roughly one in six families, but the intestacy rules still treat an unmarried partner as a stranger to the estate. Source: ONS, Families and households in the UK: 2023 (reference year 2023).
The tax position differs too. Spouses and civil partners can generally pass assets to each other free of inheritance tax and can transfer unused allowances; cohabiting partners cannot. Each person still has their own nil-rate band of £325,000 (gov.uk, as at July 2026, subject to change), but there is no equivalent spouse exemption between unmarried partners. Our guide to IHT for unmarried couples looks at this in detail, and our Inheritance Tax Explained guide covers the allowances.
Because the default rules can leave a surviving cohabitant with nothing, many people in this position choose to make a will and consider how jointly owned property is held, and often discuss it with a qualified professional. The wider estate planning guide sets out how those pieces fit together. This is general information only, and the right approach depends on individual circumstances. The government has also consulted on reform, so the legal position may change.
Sources and methodology
Every statistic on this page comes from a named official source and has been checked against the publication linked below. Family counts are UK-wide ONS estimates; couple-share and age figures come from the 2021 Census for England and Wales; the "common law marriage" belief and projection figures come from the government's 2025 consultation. Figures are as published and subject to revision by the source.
- ONS, Families and households in the UK: 2023 (published 2024): family counts and shares. View source
- ONS, Census 2021, People's living arrangements in England and Wales (Census 2021): cohabitation share by couple and age. View source
- gov.uk, A fairer end to relationships: consultation document (2025): 3.5 million couples, doubling over three decades, 47% common-law belief, 2031 projection. View source
- gov.uk, intestacy rules (as at July 2026): what happens when someone dies without a will. View source
- gov.uk, Inheritance Tax (as at July 2026, subject to change): nil-rate band and spouse exemption. View source
Frequently asked questions
How many cohabiting couples are there in the UK?
There were about 3.5 million cohabiting couple families in the UK in 2023, roughly 18% of all families, according to the ONS (ONS, Families and households in the UK: 2023). The government's 2025 consultation similarly refers to over 3.5 million couples living together without marrying or forming a civil partnership.
Are cohabiting couples the fastest-growing family type?
Cohabiting couple families have grown faster than other types in recent years. The ONS reports opposite-sex cohabiting families rose by 469,000 between 2013 and 2023, accounting for 42% of all growth in families over the decade (ONS, 2023). Growth can vary year to year, so figures are best read as a trend.
Is there such a thing as common law marriage in the UK?
No. Living together does not create a legal marriage in England and Wales, however long it lasts. The government's 2025 consultation reports that 47% of people wrongly believe a "common law marriage" status exists (gov.uk, A fairer end to relationships). Scotland has some limited cohabitant rights, but they are not the same as marriage.
Do cohabiting partners inherit automatically if there is no will?
No. Under the intestacy rules in England and Wales, a surviving cohabiting partner has no automatic right to inherit, regardless of how long the couple lived together or whether they had children (gov.uk, intestacy rules, as at July 2026). Many people in this position choose to make a will; it can be worth discussing with a qualified professional.
Do cohabiting couples get the inheritance tax spouse exemption?
No. The exemption for transfers between spouses and civil partners does not apply to unmarried couples. Each person still has their own nil-rate band of £325,000 (gov.uk, as at July 2026, subject to change), but a cohabiting partner cannot inherit tax free in the way a spouse generally can. Our IHT for unmarried couples guide explains the position.
Are the rules on cohabitation changing?
Possibly. The government ran a 2025 consultation, "A fairer end to relationships", which looked at stronger rights for cohabiting couples, including on inheritance where a partner dies without a will (gov.uk, 2025). No new law was in force in England and Wales as at July 2026, so the current rules still apply. It can be worth keeping an eye on developments.
About Fairchild Oldfield
The Fairchild Oldfield team brings together estate planning, tax, independent financial advice and client care, working with families across England and Wales.
Fairchild Oldfield are estate planning specialists and will writers, not a firm of solicitors. This article is general information based on practical experience and published statistics, not legal, tax or financial advice.
Important: This article is general information only and is not legal, tax or financial advice. Reading it does not create a professional relationship. Legal points are based on the law of England and Wales, and other UK jurisdictions, including Scotland and Northern Ireland, may differ. Statistics are attributed to their named sources and reference periods; tax figures are current as at July 2026 and are subject to change. Before acting, many people choose to seek advice from a suitably qualified professional, such as a solicitor, a STEP practitioner, an accountant, or an FCA-authorised financial adviser, who can consider individual circumstances.
