Australia · 7 min read · Laddered Editorial · 21 Feb 2026
A Complete Guide to Property Co-Ownership Agreements in Australia
Buying with friends, family or investment partners is now common in Sydney and Melbourne. A co-ownership agreement is what keeps it from going sideways. Here is what an Australian one should cover.
- legal
- agreements
- australia
- co-ownership
This article is general information only and is not legal, financial, tax, or property advice. Consider advice from a qualified professional for your circumstances.
Why this document is worth the trouble
In Sydney and Melbourne especially, buying property with someone other than a spouse has stopped being unusual. Friends do it, siblings do it, parents go in with adult children, mates pool cash for a beach shack. The maths makes sense. What gets skipped, almost every time, is the agreement between the owners themselves.
A co-ownership agreement — sometimes called a co-ownership deed or property sharing agreement — sets out who's responsible for what, who decides what, and what happens when someone wants out. It isn't legally required in Australia. Every property lawyer you'll ever speak to will still tell you to have one, because the alternative is sorting all of this out during a dispute, which is the worst possible time.
The parts that matter
Ownership structure
Australian co-owners hold title as either joint tenants or tenants in common. Joint tenancy carries a right of survivorship: when one owner dies, their share passes automatically to the others, regardless of any will. Tenants in common lets each person hold a defined percentage — say 70/30 to match the deposit — and leave that share to whoever they choose. For anyone who isn't a couple, tenants in common is almost always the right call.
How the money splits
Spell out how the purchase price, stamp duty, conveyancing and the ongoing costs — mortgage, insurance, council and water rates, maintenance — are divided. Equal or proportional to ownership, your choice, but make it explicit. (Here's how we'd think through the split itself.)
How decisions get made
Renovate, re-tenant, refinance, sell — who gets a say, and how much? Most agreements set thresholds: unanimous consent for the big calls, a simple majority for the smaller ones. Decide what "majority" means if your shares are uneven, because by headcount and by ownership percentage can give you two different answers.
How someone leaves
Cover this even though it feels premature. A workable exit clause includes a buyout mechanism, a right of first refusal for the remaining owners, and an agreed way to get an independent valuation.
How you'll resolve a fight
A mediation or arbitration step, written in before you need it, can save you tens of thousands in legal costs and a friendship besides.
The mistakes that cost the most
A few traps come up again and again:
- Relying on a handshake. "We're family, we don't need it in writing" is precisely how families end up not speaking. Get it down on paper, especially with family.
- Ignoring tax. Capital gains tax, land tax, and any stamp duty concessions can all turn on how you structure ownership. Model it before you commit, not after.
- Skipping the insurance clause. Require every owner to keep adequate cover, and name who's responsible for the policy.
- Forgetting the slow costs. Rates and routine maintenance are predictable. A reserve fund for the repairs that aren't is what stops a $6,000 surprise from becoming a $6,000 argument.
Where to get help
Laddered will help you track expenses, run governance, and keep the whole arrangement organised in one place. It does not replace a lawyer. Have a property solicitor draft or review the agreement before anyone signs — at roughly $1,500–$3,000, it's modest insurance against a problem that costs far more. Whether it's a holiday house with mates or an investment flat with your partner, the paperwork is the cheap part. Get it right while everyone's still keen.