How to Buy Out a Co-Owner in Australia: Working Out a Fair Price

When one owner wants out, someone has to put a number on it. A relationship changes, a friend wants to move on, a sibling wants their money — and suddenly a shared home has to be turned into a single, agreed figure. The trouble is that the number usually depends on years of contributions nobody wrote down. Here's how a fair buyout is actually worked out, and how to estimate yours.

What a buyout actually is

A buyout is simply one co-owner purchasing the other's share of the property, so that one person ends up owning what two used to. In practice it usually means the staying owner refinances the loan into their own name and pays the leaving owner the value of their share.

The whole exercise comes down to one question: what is the leaving owner's share actually worth today?

The fair-price building blocks

A fair buyout figure is built from three things, in this order.

1. Start with equity, not the sale price. The property's value isn't what's being divided — the equity is. Equity is what's left after the debt.

Equity = current value − outstanding mortgage − any government equity share

If a shared-equity scheme like Help to Buy holds a stake, that comes off first, because the government shares in the gain.

2. Split that equity by share. Divide the equity according to each owner's percentage — either their legal title share, or a contribution-weighted split if the mortgage and deposits were paid unequally. (We cover the three splitting methods in detail in how to calculate a fair buyout.)

3. Adjust for contributions. This is where most casual estimates go wrong. If one owner paid a bigger deposit, made extra repayments, or funded a renovation, a fair figure reflects that — otherwise the person who put in more effectively subsidises the person who put in less.

A worked example

Two owners hold a property 50/50 as tenants in common.

• Current value: $850,000
• Outstanding loan: $480,000
• Equity: $370,000

Split evenly, each owner's share of equity is $185,000 — so a first-pass buyout figure for the leaving owner is around $185,000, funded by the staying owner refinancing.

But say the leaving owner put in a $40,000 larger deposit at purchase. A fair, contribution-adjusted figure would return that difference to them — nudging their share up from $185,000 toward roughly $205,000. Same property, same value, a $20,000 swing — purely because of a contribution that would otherwise have been forgotten. That's why the running record matters as much as the valuation.

Why a written record is the real protection

Buyout disputes almost never start with the valuation — you can pay a valuer to settle that. They start with the contributions: "I paid more of the mortgage." "You never chipped in for the new roof." When there's no agreed record, it becomes one memory against another, and that's where relationships get damaged.

If every deposit, repayment, and shared cost has been tracked from day one, the buyout number is mostly already agreed before anyone sits down. There's a figure, and there's the history behind it. Nothing to argue about.

The parts to get professional help on

A buyout is a real transaction, and a few pieces genuinely need experts:

• Valuation — an independent, licensed valuer gives the most defensible figure.
• Refinancing — moving the loan into one name is a new loan application; a mortgage broker can tell you what's serviceable.
• Stamp duty — transfer (stamp) duty is usually payable on the share being transferred, though concessions can apply. Check your state's rate.
• Capital gains tax — the leaving owner may owe CGT if the property isn't their main residence.

None of these are things to guess at — but you can estimate the core equity figure yourself before you spend a cent on advice.

Estimate a fair buyout in about 30 seconds

Propact's buyout calculator does exactly the maths above: it takes the value, nets off the mortgage and any government share, splits the equity by your chosen method, and adjusts for unequal contributions — showing the net figure the leaving owner walks away with and the cash the staying owner needs to find. It handles two to four owners, so it works for investor groups and families, not just couples.

Estimate a fair buyout on the free calculator →

Or try it on a sample property in the demo to see the full equity picture first.

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This article is general information, not legal, financial or tax advice. Capital gains tax, stamp duty, and refinancing outcomes depend on your circumstances and state. Confirm any buyout figure with a licensed valuer, conveyancer, mortgage broker, and accountant before acting. Sources: moneysmart.gov.au, ato.gov.au.