Your bank's home lending manager is not legally required to act in your best interests. Your mortgage broker is. Most borrowers assume it works the other way around.
That legal asymmetry is called Best Interests Duty, and it has bound licensed mortgage brokers in Australia since 1 January 2021 under the National Consumer Credit Protection Act. A broker who breaches it faces civil penalties from ASIC. A bank staffer selling you that same bank's loan sits outside the duty entirely, because they only ever offer one shelf of products.
Timing sharpens the point. The RBA has lifted the cash rate three times in 2026, to 4.35%, and meets again on Tuesday 11 August 2026. When repayments climb, the cost of a recommendation that suited the lender more than you stops being abstract. It lands in your account each month.
What is Best Interests Duty, in plain terms?
Three obligations, written into law and enforced by ASIC under its Regulatory Guide 273.
First, a broker must act in your best interests when suggesting a loan. Not the lender's interests. Not the broker's. Yours.
Second, the conflict priority rule: if your interests and the broker's ever pull in different directions, say a lender pays a higher commission on a loan that costs you more, your interests must win. The broker cannot recommend a product because it pays better. (How Wity gets paid covers our side of that ledger, in dollars.)
Third, it has to be provable. A broker needs to show their reasoning: what they compared, what they rejected, and why the recommended loan fits your situation. At Wity that reasoning is not a filing-cabinet note. It arrives as your WityLoanPlan, a written, versioned recommendation you accept digitally, with the why spelled out beside the what.
Why doesn't the duty cover the bank branch?
Because a bank can only sell its own products, Parliament drew the line at brokers. A branch lender showing you three of their employer's loans is making a sale, not a recommendation across the market, so the law treats it as one. Nothing in the NCCP Act requires that staffer to mention the lender across the road with a sharper rate or a friendlier policy.
Branch staff are measured on their own lender's products; no rule in the legislation asks them to check the bank next door. That is not a criticism of the people. It is the structure they work inside.
The practical difference looks like this:
| Bank branch lender | Licensed broker under BID | |
|---|---|---|
| Products offered | One lender's menu | A panel, in Wity's case 45+ lenders |
| Legal duty to you | General conduct rules only | Best Interests Duty, ASIC-enforced |
| Conflict rule | None specific | Your interests must come first |
| Reasoning documented | No obligation | Required, and checkable |
| If it goes wrong | Internal complaint, then AFCA | Internal complaint, AFCA, plus ASIC penalties for BID breaches |
What does the duty look like in practice?
A worked example makes it concrete.
Farah is a pharmacist in Adelaide's inner south, earning $98,000, with a $95,000 deposit for a $630,000 townhouse. Her bank's branch offers its standard loan: she borrows at just under 85% LVR and the quote includes roughly $13,000 in Lenders Mortgage Insurance, because that bank's shelf holds no waiver for her profession.
A broker bound by Best Interests Duty cannot stop at one shelf. Assessing Farah properly means asking what she does for a living, and that question changes the answer. Under specialist lending policies available through Wity, AHPRA-registered pharmacists can borrow up to 90% with no LMI. The $13,000 fee disappears, and she is not paying interest on it for 30 years either, which is worth roughly $28,000 over the loan's life.
Same borrower. Same deposit. The difference was a legal duty to keep looking.
Based on typical scenarios. Individual outcomes vary.
How do you check a broker is doing their duty?
You do not need to read RG 273. Four questions do the work.
Ask how many lenders they compared for you, and which ones. Ask why this loan beat the runner-up. Ask what they earn on it, upfront and trail, since a broker under BID should answer without flinching. And ask for the recommendation in writing.
A broker doing the job well will have answers ready before you ask. That is the real test, more than any certificate on the wall. It is also why we built Wity the way we did: one dedicated point of contact who knows your file, and a written plan behind any recommendation, whether you are buying or weighing up a refinance.
The duty is not a slogan. It carries civil penalties, and it is the single sharpest question you can put to anyone offering you a home loan: are you legally required to put me first?
Want to see what a recommendation built on that duty looks like for your situation? Start the Wity questionnaire → Free, no credit check, two minutes.