Japan Mortgage Rate Rise SimulatorIf Your Japanese Mortgage Rate Rises, How Much More Will You Pay?
Enter your balance, remaining term and how the rate rises. The simulator includes the 5-year and 125% rules and the unpaid interest they can create.
These results are estimates based on what you enter. Many Japanese lenders review variable rates every six months, and guarantee fees, credit life insurance, prepayments and mortgage tax deductions are not included. For real decisions, check with your lender, a financial planner or official sources.
FAQ
Do payments rise right away when a variable rate goes up?
Many Japanese lenders apply a "5-year rule": the monthly payment stays the same for five years even if the rate rises. Interest is still charged at the new rate, so less of each payment goes to principal and, if the payment cannot cover the interest, unpaid interest builds up.
What is the 125% rule?
At each five-year review, the new monthly payment cannot exceed 1.25 times the previous one. Anything above the cap is deferred and remains as unpaid interest.
What does this simulator leave out?
Six-month rate reviews, prepayments, the mortgage tax deduction, guarantee fees and credit life insurance. Some lenders do not use the 5-year or 125% rules, so check your loan terms.
Related
The Bank of Japan raised its policy rate to about 1.25% on 18 September 2026 (per press reports, as of 2026-10-27).