How much deposit do I need for the next house?

What your lender is actually assessing

Your income and how reliable it is, your outgoings and other debts, the deposit or equity you are bringing, and the property itself, including the type of title and whether they will lend against it at all. Two banks can reach different answers on the same application, because the assessment belongs to each of them.

The only way to know your number is to be assessed, in writing, by the lender you intend to use. Do that before you sell rather than after, because it changes what you should be looking at and sometimes changes the order you sell and buy in.

What the Reserve Bank settings do and do not decide

The Reserve Bank limits the share of new lending a bank may write in certain categories. Under the loan to value settings effective 1 December 2025 and maintained on 14 August 2026, banks may write no more than 25% of new owner occupier lending at a loan to value ratio above 80%, and no more than 10% of new investor lending on existing property above 70%.

The debt to income settings, in place since 1 July 2024, work the same way: no more than 20% of new owner occupier lending above a debt to income of 6, and no more than 20% of new investor lending above 7, measured on gross income. There are exempted categories, including bridging finance and new build lending, and your lender can tell you whether any of them apply to you.

These are speed limits on what a bank may write as a share of its lending. They are not eligibility rules for one borrower. Lending outside them is rationed rather than impossible, so the question to put to a lender is not whether you clear a threshold, it is whether they will lend to you and on what terms.

The practical question

For most people moving house the binding number is not a ratio, it is cash. What matters is what is left after your sale settles, once the mortgage is repaid, the agency and marketing costs are paid, your legal costs are met and anything else owing on the property is cleared. That figure is your deposit, and it can be worked out well before you sell.

Work it out on your own figures rather than a rule of thumb: the numbers on your own move.