Australia’s biggest banks are united in their warning of a cash rate hike within days.

Australia’s big four banks all now warn the next hike will be within days – with one issuing a brutal wake-up call that interest rates will reach GFC-era highs by Christmas.

In a terrifying double-capitulation on Monday, Commonwealth Bank and ANZ officially abandoned their hold calls to join NAB and Westpac – uniting all big four lenders in forecasting an RBA cash rate hike to 4.60 per cent next Tuesday, September 29.

Shockingly, ANZ went a step further by dropping a double-hike bombshell, predicting back-to-back rate rises in September and November that would push the cash rate to 4.85 per cent – setting official borrowing costs back to levels not seen since late 2008 at the height of the global financial crisis.

Oil price and cash rate market pricing. Source: CBA

CBA head of Australian economics Belinda Allen

Canstar analysis reveals a 0.25 percentage point rate rise next Tuesday will add $91 a month to a $600,000 loan, $114 a month to a $750,000 loan, and $152 a month to a $1 million mortgage – and would double if ANZ’s prediction of a second hike in November plays out.

That would take a $600,000 mortgage’s cumulative increase across five total rate hikes in 2026 to a massive $456 every single month compared to what it was in January, $570 per month for a $750,000 mortgage and an extra $759 every month for a $1m mortgage compared to how it entered 2026.

ANZ’s cash rate forecasts. Source: ANZ

Canstar data insights director Sally Tindall.

Canstar data insights director Sally Tindall said ANZ has sounded the alarm for mortgage holders who would be paying nearly half a thousand dollars extra every month compared to January which was “like buying four new car tyres, not just once, but month after month”.

In an urgent report released Monday, ANZ head of Australian economics Adam Boyton and senior strategist Jack Chambers warned Middle East oil shocks were forcing RBA’s hand.

“The ongoing escalation of the conflict in the Middle East and the tendency of the RBA to view the resultant increase in oil prices as much more of an inflationary shock than a growth shock suggests that a single 25bp rate hike in November … is no longer the most likely outcome,” the report said.

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With all the big four banks flagging a September 29 cash rate increase, homeowners are being warned to shop around.

Belinda Allen, head of Australian economics for Australia’s biggest mortgage lender CBA, said the bank brought forward its forecast from November as global crude surged past $US100 a barrel.

“Our previous call was for a rate hike in November once the full quarterly CPI confirmed the materialisation of upside risks to inflation … (but) a combination of higher oil prices, stronger-than-expected economic data and increasingly hawkish signals from the RBA had shifted the balance towards an earlier move,” Ms Allen said.

Ms Tindall urged homeowners to act immediately in the coming days – before the RBA makes its next cash rate call – advising borrowers to call their current bank to haggle for a lower rate or calculate the savings of refinancing to a sharper deal before the board meets.