📈 Japan iDeCo / NISA Simulator

iDeCo and NISA contribution caps (FY2026) From the 2024 NISA reform, both NISA types allow up to ¥1.2M/year each (¥2.4M total). iDeCo contributions are tax-deductible and grow tax-free.

1. Enter your planned monthly contribution in yen.
2. Enter the investment horizon in years.
3. Enter an assumed average annual return (e.g., 4%).
4. Click Calculate to see principal, growth, and projected balance.

What is the difference between iDeCo and NISA?

iDeCo gives a tax deduction on contributions and tax-free growth but locks withdrawals until age 60; NISA gives no deduction but permanent tax-free gains and full flexibility. Both shield growth from the ~20.315% taxable-account tax.

How much can I contribute to iDeCo?

It depends on your status: self-employed persons (category 1 insured) can contribute up to ¥68,000/month; company employees ¥23,000 (¥20,000 if the company runs a DB or DC plan, ¥12,000 with both or for civil servants); dependent spouses (category 3 insured) ¥23,000; and those already receiving a public pension (typically ages 60–64) ¥12,500. Employee limits are further reduced by any employer contributions to a corporate DC plan.

Are NISA gains really tax-free forever?

Yes. Under NISA, dividends and capital gains are exempt from tax indefinitely (the つみたて variant is tax-free for 20 years; 成長 for 5 years, with both designed to be rolled or kept). There is no annual tax on the growth.

Why does the tax-free status matter so much?

In a normal brokerage account, gains are taxed at 20.315%, which compounds against you over decades. A tax-free wrapper lets the full growth reinvest, noticeably enlarging the final balance.

Can I withdraw iDeCo before 60?

Generally no — iDeCo is locked until age 60 (with narrow exceptions like disability). That illiquidity is the trade-off for the upfront tax deduction and tax-free growth.

This tool is for informational purposes only and does not constitute financial advice. Consult a qualified financial professional for advice specific to your situation.

Time and return rate dominate the outcome far more than the vehicle choice, so start early and keep contributions steady through market dips. iDeCo's deduction lowers your taxable income now, which is most valuable if you are in a higher bracket, while NISA's flexibility suits people who may need access before 60 or who have already maxed iDeCo. Watch the annual and per-account contribution caps (iDeCo ¥12,000–¥68,000/month depending on status; NISA ¥1.2M/year for つみたて). Reinvesting gains rather than withdrawing them is what compounds — and the tax-free wrapper protects every yen of that compounding. Pair this with the public pension estimator to see how much of your retirement the public system covers and where the gap (filled by iDeCo/NISA) actually is.