We live together but aren’t married — what happens when one of us dies?

Why so many couples get this wrong

In England and many common-law countries, people assume long-term partners are protected, or that “common-law marriage” exists — it largely doesn’t, and abroad the gap is wider. In the civil-law countries where you’ve retired or bought a home, succession law is built around marriage and bloodline. A cohabiting partner usually falls outside the list of legal heirs entirely. So when one partner dies:

• their share of the home and their accounts pass to their children, parents or other relatives under the rules — not automatically to the survivor;
• the survivor may have no legal claim to the deceased’s own assets;
• and the tax can be heavier: in some countries a partner who isn’t married or registered pays the higher stamp-duty/tax rate that close family avoid. (In Portugal, a partner in a recognised união de facto is exempt, like a spouse — but still needs a will to inherit.)

It differs by country — and none of it is automatic

Each country treats cohabitation differently, and the protections are partial at best — but in none of them does living together, by itself, make your partner your heir:

• Portugal — união de facto (Lei 7/2001): a recognised status after two years, giving the survivor certain protections (notably around the family home, and in some cases a survivor’s pension) — but not the status of heir. A will is still needed to leave them your assets — and, unlike in some countries, a recognised partner pays no Portuguese stamp duty on what the will leaves them.
• Spain — pareja de hecho: the rules are regional. Under the common Civil Code a partner is not an heir; but Catalonia (and some other regions) give a registered or stable partner rights close to a spouse’s — so the region decides, and has to be checked.
• Italy — convivenza di fatto (Legge 76/2016, the “Cirinnà” law): gives cohabitants some rights, including around the shared home, but not a share of the estate. A registered unione civile (open only to same-sex couples) is treated like marriage; a simple convivenza is not — so a will is needed.
• France — PACS: a civil partnership that carries real tax advantages for the survivor but, on its own, does not make the partner an heir — French law still passes the estate to children or other relatives unless a will (and the right planning) provides otherwise.

So the honest position is the same across all four: don’t rely on cohabitation status alone. (The precise regional and per-status detail in Spain, Italy and France is confirmed for your specific situation.)

What protects the survivor

Two tools, used together, usually solve it: a will that leaves the partner what you intend (within the forced-heirship limits, or using a Brussels IV choice of your national law to widen what’s possible), and structuring the home or assets so the survivor is secure. Married couples have far stronger automatic protection — so for some couples, marriage itself is part of the answer. The key point is simply: it must be done in advance.