See the cost and LVR gap for buying back a co-owner’s share.

These are example figures
Change any of them and the answer updates straight away.Start with the figures that change what you might need to pay.
Check the scheme and the figures you can confirm.
Adjust the rate, term and offset to match your loan.
Set the property growth and projection length.
Your answer
Extra cash to buy back today
$7,500
At your 80% target LVR; lender serviceability is not assessed
To buy back 25% today, you would need $7,500 in cash alongside a $600,000 loan.