Craigieburn Family's $690k Upsize Shows Mortgage Math Squeeze

Their selling agent, Ray White's Trish Orrico, said interest rates "had to come back up" but that most sellers are factoring the change into their plans rather than being forced into a sale. Orrico said she is encountering people selling for less than they paid, though this is more often tied to life changes — including selling properties in their super fund — than rate pressure alone. "There are people with no choice but to get on with it. And they are buying off other people in a similar boat," she said.

This dynamic — upsizers absorbing both a smaller sale price and a bigger loan simultaneously — creates pressure for families attempting to trade up during a cooling market. The Zwagermans have responded by tightening weekly budgets, reducing discretionary spending and considering increased work hours for Ms Zwagerman, who is currently part time.

Why the Timing Compounds the Squeeze

The mechanics here matter. An upsizing buyer doesn't just face a higher purchase price — they face a higher price financed at a higher rate, on a larger loan balance, right as their existing asset may be selling for less than expected. Current mortgage market data shows Big Four lenders averaging a 6.79% variable rate against an RBA cash rate of 4.35%, which was last moved in May 2026 via a hike from 4.10%. Any further increase lifts repayments on the larger post-upsize loan more than it would have on the smaller original loan — the family is effectively more exposed the moment they trade up.

Separately but relevantly, The Age reports that prestige suburbs have seen significant price declines, with median prices falling sharply, whilst more affordable areas around the $700,000-$900,000 range have recorded growth.

This split matters for the Craigieburn family: their $660,000-$690,000 home sits near the affordable band showing resilience, but whatever they buy next likely sits in a higher bracket where buyer caution is building.

Auction clearance data shows Melbourne running at 56% against Sydney's 45%, Brisbane's 20% and a 46.5% national average — evidence the market still clears stock, but at a rate that leaves little room for sellers banking on competitive bidding to offset rate-driven repayment increases.

Background: How Gearing and Borrowing Capacity Interact

Families moving up the property ladder are, in effect, re-entering the borrowing capacity test that all mortgage applicants face under APRA's serviceability settings. The size of loan a lender will approve is shaped by current rates, the applicant's income, and a built-in buffer above the actual rate charged — meaning a rate rise doesn't just cost more each month, it can also shrink what a bank is willing to lend in the first place. For readers assessing how debt structure and rental income interact with tax outcomes, the fundamentals are covered in Negative Gearing vs Positive Gearing, though the Craigieburn case concerns an owner-occupier upsize rather than an investment purchase. Investors watching the same rate cycle for deductible loan costs may also find Australian Property Tax Guide — What Every Investor Needs to Know useful background.

The broader pattern in Melbourne's current cycle — weakness concentrated at the top, resilience at the bottom — has a precedent in prior downturns, where high-value properties typically correct first because discretionary sellers can wait out soft conditions whilst necessity sellers in the affordable band cannot. PRD chief economist Dr Diaswati Mardiasmo told The Age loan sizes scale sharply with price: a loan on a $900,000 house might sit around $600,000, whilst a Toorak purchase above $2 million could mean borrowing over $1.5 million, a gap that "really" impacts monthly budgets when rates move.

What This Means for Buyers and Sellers

For families in the Zwagermans' position, the practical lesson is to model the new mortgage at a rate above today's advertised figure before committing to an upsize auction. With Big Four variable rates sitting near 6.79% and the cash rate at 4.35%, a single RBA move changes both what a lender will approve and what the monthly repayment actually costs once settled. Buyers should get pre-approval refreshed close to auction day rather than relying on figures from months earlier, given how quickly sentiment can shift.

For sellers in the affordable band — anywhere near the $700,000-$900,000 range The Age identifies as the current growth pocket — competition from first home buyers and reduced borrowing capacity elsewhere is funnelling demand towards cheaper stock, which should support clearance outcomes even as prestige suburbs soften. Ray White South Morang agent Nick Petrovski told The Age that well-presented homes "sub a million are selling and are well inspected," and that results remain "very strong, irrespective of outside noise" in suburbs like Epping, Mernda and Bundoora.

For upsizers specifically, the Craigieburn case is a reminder that trade-up transactions carry compounded rate risk — exposure on the sale side and the purchase side simultaneously. Running the numbers on both legs of the transaction, and building in a buffer above current advertised rates, is the only practical defence whilst the RBA's next move remains unresolved just days after this family's own auction date.