Your lender advertises one rate. It tests you on another — three full percentage points higher. That gap is the APRA serviceability buffer, and after three RBA hikes in 2026 it has teeth again: with variable home loan rates sitting in the mid-sixes, most new borrowers are now assessed at rates north of 9%. A rate you may never pay is setting your price ceiling.
The timing is no accident. The RBA lifted the cash rate in February, March and May 2026, held it at 4.35% in June, and meets again on 11 August 2026. In the middle of that tightening run, on 28 May 2026, APRA reviewed the buffer and left it exactly where it has sat since October 2021: 3 percentage points.
Rising rates do carry a consolation prize. Cotality put national auction clearance in the low 40s in June 2026, which hands a prepared buyer more negotiating room than anything on offer during the 2021 frenzy. Prepared means knowing your true borrowing capacity before you bid, and the buffer is the biggest single number standing between you and that figure.
What is the serviceability buffer, and who set it at 3%?
APRA, the regulator that supervises Australian banks, requires lenders to test whether you could still repay your loan at your actual interest rate plus at least 3 percentage points. Apply for a variable loan at 6.15% and the bank models your repayments at 9.15%. Pass, and you're serviceable. Fall short, and the loan shrinks until you do.
The buffer rose from 2.5 to 3 percentage points in October 2021, when the cash rate was 0.10% and APRA worried borrowers were loading up at rates that could only go one way. They went that way. In its 28 May 2026 review, APRA could have trimmed the buffer. It held.
In plain English: the buffer is altitude training for your home loan. You qualify in the thin air above 9%, so repayments at your real rate feel breathable, even if the RBA keeps climbing from here.
One wrinkle worth knowing. Most lenders also carry a floor rate, a minimum assessment rate that applies when actual rates are low, and you're tested at whichever is higher: the floor, or your rate plus 3%. In 2026, with rates elevated, the plus-3% test wins at nearly all lenders.
Why does the same 3% bite harder in 2026?
A buffer is only as heavy as the rate underneath it. In 2021, that 3% sat on top of variable rates near 2.5%, producing assessment rates around 5.5%. Now it sits on top of rates above 6%, and assessment rates have pushed past 9%. Your income didn't change. Your ceiling did.
You've been comparing advertised rates. Your lender has been comparing you against a rate that appears on no comparison site.
Follow the chain through. APRA held the buffer while the RBA was hiking, so each 0.25% rise lifts assessment rates in lockstep. A household that qualified for $750,000 against a January pre-approval may no longer qualify for it in July, because pre-approvals are tested at the rates of the day, not the rates you started with. Anyone planning a spring purchase should re-model capacity now, at today's assessment rates, rather than trusting a number from two hikes ago.
Where rates head next is contested. The big four banks' economists disagree: Westpac pencils in two more hikes to a 4.85% peak; CBA, NAB and ANZ argue the peak has passed, with cuts from 2027. The buffer exists precisely because nobody can promise you which camp wins.
The buffer also gained a companion this year. Since 1 February 2026, APRA caps how much new lending a bank can write at a debt-to-income ratio of six times or higher: no more than 20% of new owner-occupier and investor loans. Two gates now, not one.
How much borrowing power does the buffer take?
Meet Alicia and Marcus, a physiotherapist and a project manager buying an $800,000 townhouse in Chermside on Brisbane's northside. They have a $120,000 deposit and need $680,000 over 30 years. Their lender's variable rate is 6.10%.
| On a $680,000 loan over 30 years | At the advertised 6.10% | At the 9.10% assessment rate |
|---|---|---|
| Monthly repayment | $4,121 | $5,520 |
| Annual repayment | $49,452 | $66,240 |
| Loan the same $5,520/month could service | ~$911,000 | $680,000 |
The lender doesn't ask whether they can afford $4,121 a month. It asks whether they can afford $5,520. The buffer alone trims roughly $231,000 from what their repayments could otherwise service. About a quarter of their capacity, gone before a single living expense is counted.
And that's the clean version: no car loan, no HECS balance, no buy-now-pay-later habit for the assessor to annualise. Each of those shrinks the number further.
Illustrative rates as at July 2026; actual rates and comparison rates vary by lender and change often. Based on typical scenarios. Individual outcomes vary.
Can the buffer block your refinance?
The strange part: the buffer can see you declined for repayments smaller than the ones you already make. Say you're paying 6.85% and apply to switch to a lender offering 6.10%. That new lender must assess you at 9.10%. If your circumstances have shifted since your original approval, you can fail the test for a cheaper loan while paying a dearer one on time, month after month.
One myth needs killing here: your current bank is not holding you hostage. You're free to discharge your loan and leave whenever you like (break costs on fixed loans aside). The barrier is passing the new lender's assessment. Three reasons dominate the declines: an LVR above the new lender's threshold, the buffer itself, and changed circumstances since your last approval. A new baby. A drop to part-time. A car loan you'd forgotten counts.
We've watched a $12,000 credit card limit, untouched for years, tip a refinance from approve to decline. Assessors service the limit, not the balance.
The LVR barrier has more give than most borrowers realise. Under specialist lending policies available through Wity, any borrower can refinance at up to 85% LVR with no LMI; nurses, midwives, allied health and senior professionals at up to 90%; doctors and dentists at up to 95%. If equity is what's blocking your application, those thresholds are the escape routes.
What can you do about the buffer before you apply?
You can't negotiate with APRA. You can control most of what the buffer multiplies.
- Cut credit limits, not just balances. Lenders assess cards as if fully drawn. Closing an unused $10,000 limit can restore tens of thousands of dollars in capacity.
- Check your HECS position. Since 30 September 2025, lenders have been permitted to exclude HELP debts within roughly 12 months of being cleared from serviceability. If yours is nearly gone, your numbers change: how HECS affects borrowing power.
- Don't fix expecting to dodge the test. Lenders typically apply the buffer to the revert rate on shorter fixed terms, so fixing rarely lifts capacity on its own. The fixed vs variable decision is about repayment certainty, not beating the assessment.
- Trim spending three months before you apply. Lenders read your statements against the HEM benchmark and use the higher of the two, so a disciplined quarter shows up in your assessed capacity.
- Model across lenders, not within one. Floor rates, expense treatment and income shading differ from lender to lender, and the same payslips can produce capacity gaps of $100,000 or more. The Wity Borrowing Power Assessment models your capacity across 45+ lenders, not one bank's calculator, with the buffer, the DTI caps and each lender's quirks built in.
Your rate isn't your rate. The assessment rate is. Better to meet it on your own terms, months before a contract is on the table.
Want your real number, buffer included? Start the Wity questionnaire → — free, no credit check, two minutes.