Australia · 7 min read · Laddered Editorial · 26 Jun 2026

Unequal Deposits: How to Work Out Ownership Percentages When You Buy Property Together

One of you has $80,000 saved, the other has $40,000, and you both want in. Here's how Australian co-buyers turn uneven contributions into ownership shares nobody resents later.

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This article is general information only and is not legal, financial, tax, or property advice. Consider advice from a qualified professional for your circumstances.

The question everyone fudges

Two friends decide to buy together. One has $80,000 saved, the other has $40,000. They agree it'll "all come out in the wash", put both names on the title, and move on to arguing about suburbs.

That wash never comes. Unequal contributions cause an outsized share of co-ownership grief, because the difference is real money and nobody wrote down what it meant. The maths, happily, is simple. Deciding what the maths should be is the part that needs care.

Start with what the title says, because the law will

Do nothing, and the law does something for you — probably not what you intended. Put two names on a title without specifying shares and you'll generally be taken to own the place equally, whatever your bank statements say about who funded the deposit. A handshake deal to "sort out the extra $40k when we sell" has no standing on the title, and proving a private arrangement after a falling-out is slow, expensive and uncertain.

Australian co-owners who want unequal shares hold the property as tenants in common, which lets each person hold a defined percentage — 60/40, 70/30, whatever reflects reality. (Joint tenancy, the default for many couples, doesn't do percentages at all, and its survivorship rules are usually wrong for friends and siblings. Our co-ownership agreement guide covers the difference.)

So the first decision isn't "how do we track this". It's "what number goes on the title".

Two clean ways to set the number

Shares follow total contribution. Add up what each person is putting in and will pay ongoing, and set the title to match. Say the property costs $800,000 with $120,000 of deposit and upfront costs, and you'll split the repayments on the $680,000 loan equally:

Person A: $80,000 deposit plus half the loan — $420,000 of the $800,000 total, or 52.5%
Person B: $40,000 deposit plus half the loan — $380,000, or 47.5%

Title reads 52.5/47.5 as tenants in common, and every dollar of sale proceeds later just follows the percentages. Clean, and nothing to remember.

Equal shares, unequal contributions handled separately. Keep the title 50/50 but have the person who put in less pay more of the mortgage until things even out — or treat the deposit gap as a documented loan between you. This suits people who genuinely want an equal partnership but arrived with unequal savings.

Both work. What doesn't work is the third, most popular model: equal title, equal repayments, and a vague memory that someone put in more. That isn't a model. That's a deferred argument.

The tax trap almost nobody sees coming

If the property will earn rent, there's an ATO rule that catches a lot of co-owners off guard: rental income and expenses must be declared in line with your legal ownership interest — the one on the title. The ATO's ruling on this (TR 93/32) is blunt about private side deals: an agreement between co-owners to split the money differently has no effect for income tax purposes.

So if the title says 50/50 but you privately agreed 70/30, the ATO still taxes the rent 50/50, and negative gearing deductions follow the same split. If you want the tax outcome to match the economics, the title has to match the economics. And it's worth getting right at settlement rather than patching later, because changing title shares down the track can itself trigger stamp duty and capital gains consequences.

The mortgage doesn't care about your percentages

Here's the uncomfortable bit. However you split the title, a standard joint home loan makes each borrower liable for the whole debt, not their share of it. If your co-owner stops paying, the bank looks to you for every dollar — 52.5% ownership notwithstanding.

Some lenders offer structures that soften this, where each co-owner carries their own loan against the shared property; we cover how those work in our guide to property share loans. Either way, your ownership split and your loan structure are two separate decisions, and it pays to make them deliberately, together. Our mortgage guide walks through the borrowing side.

What to actually write down

Whichever model you pick, the paperwork is short — but it has to exist:

The title shares, registered as tenants in common in your agreed percentages.
A co-ownership agreement recording how you arrived at the split, how ongoing costs divide, and what happens to extra contributions, like one owner funding a renovation. (What to include is here.)
A record of every contribution from day one. The deposit is easy to remember. The $3,100 hot water system in year two, and who covered the rates in a tight month, are not. When you sell in year nine, that ledger is the difference between a calculation and a negotiation.

The last point is where most arrangements quietly fail. The split you agreed at settlement only stays fair if the record of what everyone actually paid stays accurate for the life of the property.

Keep the number honest

This is the problem Laddered was built for: you set your ownership percentages and contribution rules once, and every expense after that splits by those rules automatically, with one ledger everyone can see down to the cent. The agreement stays the agreement, instead of drifting into "I'm fairly sure I paid more than you last year."

It doesn't replace a lawyer. Have a property solicitor paper the title structure and the co-ownership agreement before settlement, especially if the shares are unequal. The maths is the easy part; making it stick is what you're paying for. Do it while the only disagreement you have is about suburbs.