A bank may offer a lower mortgage rate and a cash rebate, making refinancing look like an easy saving. In reality, you are closing one mortgage, applying for another and completing a new valuation and legal process. Each part can carry a cost.
Collect six figures before comparing offers
Start with the outstanding principal and the old bank's actual redemption amount. Then obtain any penalty, clawback of the original cashback, the new bank's approved rate and term, all legal or administrative costs, and the new valuation. A promotional “rate from” is not an approval.
The HKMA mortgage consumer information specifically reminds borrowers to consider administration, legal, insurance and valuation costs, and notes that a calculator cannot reflect every approval factor or mortgage term.
Treat cashback as an offset, not a profit
A practical first calculation is:
Net refinancing cost = penalty + old cashback clawback + legal and valuation costs + administration fees − new cashback
If the result is positive, monthly savings must recover that amount before the refinance produces a net benefit. If it is negative, the upfront rebate is still not proof that lifetime interest is lower. The new cashback can come with another lock-in or penalty period, which matters if the property may be sold or the loan repaid again soon.
Break-even is useful, but it can hide a longer loan
If net costs are HK$12,000 and the monthly payment falls by HK$1,000, a simple break-even estimate is 12 months. That is relevant when you may sell soon.
The trap is resetting an 18-year remaining mortgage to 30 years. The new payment falls sharply because repayment is spread over more months, even if total interest rises. Compare the current and new payment, net costs, break-even month, remaining interest, new total interest and both payoff dates together.
Use the Mortgage Refinance Calculator with the outstanding balance, both rates and terms, cashback and confirmed costs. If the goal is total-interest saving, compare similar remaining terms. If the goal is monthly cash-flow relief, say so explicitly and recognise the longer debt period.
A lower valuation can create a cash gap
The new lender's valuation can be below the owner's expectation. If the approved mortgage is insufficient to redeem the old loan, the borrower must fund the difference. The new lender will also reassess income, existing debt and repayment history; approval obtained years ago from the current bank does not guarantee the same amount today.
Compare the rate mechanism, not only today's rate
For H-plan and P-plan mortgages, record the reference rate, margin, cap, rebate and promotional period. Test at least an unchanged-rate case, a one-percentage-point increase and a one-point decrease. A refinance that works only under the most optimistic rate path has little margin for error.
Refinancing and equity release are different decisions
A straightforward refinance replaces the old outstanding debt. A top-up or equity-release loan increases principal. Extra cash can be useful for renovation or another purpose, but it also increases interest and puts the home behind a larger secured debt. Assess the additional borrowing separately rather than calling it free cash because the total monthly payment looks similar.
Before signing
- Has the old bank confirmed redemption, penalty and cashback clawback in writing?
- Are the new rate, cap, term and cashback formally approved?
- When is cashback paid, and what new penalty period applies?
- Who pays legal, valuation and administration fees?
- How much cash is required if valuation is lower than expected?
- Is the payment lower because the rate fell, or because the term was extended?
- Will you hold the property long enough to pass the break-even point?
If you already have cash available, also compare staying with the current bank and reducing principal through the Mortgage Prepayment Calculator. Refinancing and prepayment solve different problems and should not be bundled merely to obtain a rebate.
Official references
The useful question is not how large the cashback appears. It is whether total cost remains lower after penalties, fees, valuation gaps and the new repayment term—and whether the saving arrives before your expected next move.