Mortgage And Household Finance Series
This series looks at mortgages not from the standpoint of “how much can I borrow,” but from household cash flow and risk management.
- Flat 35 Tops 3% for the First Time: A 50 Million Yen Loan Can Change Total Repayments by About 28.8 Million Yen (this article)
- Comparing Fixed and Variable Rate Scenarios for a 50 Million Yen Mortgage
- Mortgage Repayment Ratios by Income: What Is the Real Safe Zone?
- How to Calculate a Mortgage Amount That Is Harder to Break Your Household Budget
- Is Mortgage Prepayment Really Worth It?
- Is a Mortgage an Asset or a Liability?
- Using the New NISA While Carrying a Mortgage
- How to Avoid Buying “Negative Property”
[Summary]
On June 1, 2026, the rate on Japan’s long-term fixed-rate mortgage product Flat 35 rose sharply.
According to reports, the lowest rate for repayment terms of 21 to 35 years reached 3.21%, exceeding 3% for the first time since the current system began in October 2017.
When home prices remain high and mortgage rates rise at the same time, the decision for buyers becomes much heavier.
The question is not simply whether a fixed or variable rate is “better.”
The real question is whether your household should bear future interest-rate risk through a variable-rate loan, or pay more upfront to lock in repayment amounts through a fixed-rate loan.
This article uses a 50 million yen, 35-year mortgage to compare a 3.21% fixed-rate Flat 35-style loan with a variable-rate case where 0.50% continues throughout. It then outlines who may be better suited to fixed rates and who may be able to consider variable rates.
This article is not a recommendation to enter into any mortgage contract. Actual rates, fees, group credit life insurance, rate reduction programs, screening conditions, and repayment amounts differ by lender and borrower. Check with lenders and qualified professionals before signing.
Why Flat 35 Rose to 3.21%
Flat 35 is a long-term fixed-rate mortgage offered through cooperation between the Japan Housing Finance Agency and private financial institutions.
Its defining feature is that, in principle, the interest rate and repayment amount determined at borrowing remain unchanged until the end of repayment. This makes it easier to avoid the risk of monthly payments rising due to future rate increases.
However, long-term fixed rates are sensitive to long-term interest rates. When Japan’s long-term rates rise, fixed-rate mortgages such as Flat 35 face upward pressure.
At 3.21%, the psychological burden for homebuyers is substantial. The fixed payment offers comfort, but the monthly payment becomes heavy.
The necessary question is not “fixed or variable” in the abstract. It is how much rate risk your household can actually absorb.
Flat 35 vs Variable Rates
Fixed and variable rates differ not only in headline rate levels, but in who bears the interest-rate risk.
| Item | Flat 35 / Full-Term Fixed | Variable Rate |
|---|---|---|
| Rate level | Reported at 3.21% in June 2026 | Many products remain in the 0.3% to 0.5% range |
| Repayment amount | Generally fixed at borrowing | Can rise if rates rise |
| Household planning | Easier to plan long-term costs | Lower initial payment |
| Main risk | High initial burden; expensive if low rates persist | Higher repayment and interest burden if rates rise |
| Better suited for | Households that want fixed payments and lower rate risk | Households with savings capacity and flexibility to prepay or adjust spending |
Even with a fixed rate, household risks do not disappear. Education costs, repairs, property tax, management fees, income decline, job changes, illness, and inflation remain.
Fixed rates mainly remove the risk that the mortgage payment itself rises because rates rise.
How Different Are Total Repayments on a 50 Million Yen Loan?
Assume a 50 million yen loan over 35 years.
The variable-rate case assumes 0.50% remains unchanged for all 35 years. This is a strong assumption and should be seen as a “very favorable variable-rate scenario,” not a forecast.
Loan amount: 50 million yen
Term: 35 years
Repayment method: Equal principal and interest
Bonus payments: None
Fees, guarantee fees, insurance differences, taxes: Excluded| Rate type | Monthly repayment | Total repayment over 35 years | Total interest |
|---|---|---|---|
| Flat 35-style fixed rate at 3.21% | About 198,333 yen | About 83.30 million yen | About 33.30 million yen |
| Variable rate at 0.50% for 35 years | About 129,793 yen | About 54.51 million yen | About 4.51 million yen |
| Difference | About 68,540 yen | About 28.79 million yen | About 28.79 million yen |
On the surface, the variable-rate case looks much lighter.
The monthly gap is about 68,500 yen. Over 35 years, the difference is about 28.79 million yen.
But that gap exists only under the assumption that the variable rate remains at 0.50% for 35 years. If rates rise, the gap narrows. Depending on the timing and scale of rate increases, the ranking can change.
This 28.79 million yen is not proof that variable rates are always better. It is a way to measure how much “insurance premium” a borrower may pay to avoid future rate risk by choosing a fixed rate.
The Hidden Weaknesses of Fixed Rates
In a rising-rate environment, the certainty of fixed rates becomes attractive. But with a loan as large as 50 million yen, fixed rates place a large fixed cost on the household.
Monthly Payments Are High, Slowing Savings
In this example, the monthly gap between 3.21% fixed and 0.50% variable is about 68,500 yen.
That is a large amount for most households. It can reduce the ability to build cash for education, cars, repairs, moving, illness, or job changes.
Fixing the mortgage payment is useful, but if it removes all household flexibility, it becomes dangerous.
It Becomes Harder to Build Prepayment Funds
Higher monthly fixed-rate payments make it harder to build cash for future prepayments.
There are cases where a household chooses fixed rates to avoid rate risk, but then becomes weaker against other risks because cash reserves are thin.
Mortgage planning is not only about interest rates. Liquidity matters.
It Can Reduce Investment Opportunities
If the monthly difference of about 68,500 yen could instead be saved or invested through the new NISA over the long term, future financial assets could look very different.
Investment carries risk and is not guaranteed to earn 4% or 5%. Still, choosing a fixed rate narrows the option to use lower initial payments for savings and investment.
Who May Still Prefer Fixed Rates at 3.21%
Fixed rates are expensive, but expensive does not mean unnecessary.
| Household situation | Why fixed rates may make sense |
|---|---|
| Repayment capacity is not large | Higher payments from rate increases could destabilize the household |
| Education costs will rise | Housing costs can be fixed before future spending increases |
| Income upside is uncertain | The plan does not depend heavily on raises or dual income continuing |
| Rate news causes strong anxiety | Psychological burden can be reduced |
| The home is likely to be held long term | Long-term spending can be planned more easily |
Fixed rates are close to insurance against rising rates. The premium is high, but for households that cannot afford a major repayment shock, the premium may have value.
Who Can Consider Variable Rates
Variable rates may be an option for households that have ways to absorb rate increases.
| Household situation | Why variable rates may be easier to choose |
|---|---|
| Cash and financial assets are sufficient | Prepayment or principal reduction is possible if rates rise |
| Monthly savings capacity is high | Higher repayments can be absorbed through household adjustment |
| The repayment period will be shortened | Exposure to rate changes can be reduced |
| A sale or move is likely in 10 to 15 years | The household may not bear 35 years of rate risk |
| Household income has growth potential | Higher repayments may be absorbed by income growth |
Variable rates should not be chosen only because they are cheap at the start.
The key is how much increase the household can tolerate. Can it still protect education spending and daily life if monthly payments rise by 30,000 yen, 50,000 yen, or 80,000 yen?
The Final Test Is the Repayment Ratio
Flat 35 crossing 3% in June 2026 is a clear sign that Japan’s mortgage environment is changing.
But fixed versus variable should not be decided by headlines alone.
The number to watch is the repayment ratio.
Repayment ratio = Annual repayment amount ÷ annual incomeAt 3.21%, a 50 million yen loan produces a monthly payment of about 198,333 yen, or about 2.38 million yen per year.
For an annual income of 7 million yen, the repayment ratio is about 34%. For 9 million yen, it is about 26%. For 12 million yen, it is about 20%.
The same 50 million yen loan feels completely different depending on income, family structure, education costs, car ownership, and savings.
Mortgage planning is not about finding the cheapest rate. It is about deciding how much fixed cost and interest-rate risk your household can carry.
Now that fixed rates have moved above 3%, mortgage decisions should be worked backward from a repayment amount the household can withstand, not from the maximum amount a lender will approve.
Sources
- Japan Housing Finance Agency / Flat 35, “Flat 35 Product Lineup”
- KAB ONLINE, “Flat 35 June Minimum Rate Tops 3% for the First Time on Long-Term Rate Rise” (June 1, 2026)