Compare your mortgage with a refinance.
Net benefit over term
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Current payment
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New payment
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Monthly saving
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Your breakdown
Updates live as you type| Step | Amount (HKD) |
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Worked example
Suppose you owe HK$4,000,000 with 20 years left, currently at 4.0 percent, and a bank offers 3.4 percent plus a HK$40,000 cash rebate, with HK$10,000 of legal fees. The current monthly repayment is about HK$24,239. At the new rate the repayment drops to about HK$22,993, a saving of roughly HK$1,246 a month. Over the remaining 240 months that saving totals about HK$299,002. Adding the HK$40,000 rebate and subtracting the HK$10,000 legal fees leaves a net benefit of about HK$329,002 across the full term. The saving is worthwhile here, but watch the rebate clawback window, usually two to three years, during which repaying early forces you to return the rebate.
How it is calculated
The tool prices both mortgages as standard repayment loans on the same outstanding balance and the same remaining term, so the only difference is the interest rate. Each monthly repayment uses the annuity formula, where the payment equals the balance times the monthly rate, divided by one minus one plus the monthly rate raised to the power of minus the number of months. The monthly saving is simply the current repayment less the new repayment. That saving is multiplied by the number of months remaining to get the lifetime gross saving, then the cash rebate is added and the legal and valuation fees are subtracted to reach the net benefit. The result assumes you keep the loan for the full term, so if you expect to repay or move within the clawback period, reduce the rebate accordingly.