Buying with someone you are not married to

There is a settled way of talking about joint ownership. It is worth asking how much of it survives contact with the detail.

The default may not suit you

Most systems offer a form of joint ownership where the survivor automatically takes the whole, and another where each holds a defined share. The first suits couples intending everything to pass to the survivor; the second suits unequal contributions or separate estates. Choosing without understanding the difference is common and consequential.

The choice is not usually permanent, since most systems allow the form of holding to be changed later by a formal notice or deed, which matters when a relationship changes and is one of the first things worth doing at that point rather than one of the last.

Document unequal contributions

Where one party puts in a larger deposit, a declaration of trust or equivalent records the shares and how proceeds are divided. Without it, a court may treat the beneficial interest differently from what either party assumed. It costs a modest legal fee at purchase and is expensive to reconstruct in a dispute.

A useful declaration covers considerably more than the opening deposit, setting out how the mortgage payments, the bills, any later capital works and a parental gift or loan are to be treated, because a party who paid two-thirds of the mortgage for a decade with nothing in writing is in much the same position as one who never recorded the deposit.

Cohabiting is not marriage in law

In many jurisdictions there is no such thing as a common-law spouse, whatever the length of the relationship. Rights on separation and on death can be minimal without documentation, regardless of contributions made. This surprises people consistently and is worth confirming for your own jurisdiction.

In practice, the gap extends well past the house, since pension death benefits, the right to be treated as next of kin, and the tax treatment of anything inherited can all differ for an unmarried partner, and each of those is fixed by a separate nomination or document rather than by the property paperwork.

Cover the exit at the start

Agreeing in advance what happens if one party wants out — a right of first refusal, a valuation method, a notice period — prevents the worst version of that conversation. It is much easier to agree while both parties are content. Recording it alongside the declaration of trust costs almost nothing extra.

The mechanisms that actually work are the dull ones: a stated method for obtaining a valuation and what happens when two valuations differ, a period in which the remaining party may buy the other out, and a default that the property is sold if they cannot — because an agreement to agree resolves nothing at the moment it is needed.

Wills matter more than people think

Where ownership does not pass automatically to the survivor, a will determines who receives a share. Intestacy rules frequently do not favour an unmarried partner, and can leave them living with a stranger's inheritance. Two simple wills at the point of purchase close that gap.

Wills need maintaining rather than making once, since in several jurisdictions marriage automatically revokes an existing will while separation may not, so the document that protected an unmarried partner can quietly stop applying at precisely the point the circumstances changed.

None of this is a substitute for talking to a clinician if something feels wrong.

The mortgage does not divide when you do

A joint mortgage is normally a joint and several liability, meaning each borrower is answerable for the whole payment rather than for a share, and a missed payment marks both credit records regardless of whose turn it was. A declaration of trust governs the relationship between the owners and does not bind the lender at all, so an agreement that one party takes seventy per cent of the proceeds does nothing whatever to release the other from the loan.

Removing a name requires the lender to accept that the remaining borrower can carry the mortgage alone, which is an affordability assessment rather than a formality and is frequently the point at which a separation stalls for months. Life cover and income protection on both parties are the usual answers to the version where one person dies or cannot work, and how those are arranged, held and taxed varies by jurisdiction, which makes it a conversation for a regulated adviser rather than a decision to take from a template.

The takeaway

Decide how you hold it, write down the shares, and make wills. All three at purchase.

Pick the one that costs you least, and let the rest wait.