New NISA vs iDeCo: Differences, Which to Prioritize, and Using Both

Japan's new NISA and iDeCo both let your investment gains grow tax-free, but their purpose and usability differ greatly. The new NISA is a flexible account you can withdraw from anytime, while iDeCo is a retirement-only scheme that locks money up until age 60 in exchange for deducting contributions from your income. Many people wonder which to prioritize and whether they can use both. This article organizes the differences axis by axis and explains how to choose and prioritize based on your situation.

The basic difference between new NISA and iDeCo

The only thing these two share is "tax-free investing." The new NISA is a flexible account for general wealth building, while iDeCo trades flexibility for stronger tax breaks and is dedicated to retirement funds.

*From the December 2026 contribution (debited in January 2027), the iDeCo limit rises to up to 900k yen a year (75k yen a month for the self-employed), and people who meet certain conditions can contribute until age 70.

How the tax exemption works

New NISA: tax-free gains

Normally, profits from funds or stocks are taxed at about 20.315%. Inside a NISA account, capital gains, dividends, and distributions are entirely tax-free. The lifetime tax-free limit is 18M yen (of which 12M yen is the growth quota), and the quota is restored the year after you sell. See how much you could grow with the NISA simulation.

iDeCo: tax-free gains plus income deduction

iDeCo gains are also tax-free, but it adds a powerful benefit NISA lacks: contributions are fully deducted from income, directly cutting your yearly tax by roughly your contribution times your tax rate (for example, about 48,500 yen a year under the 2026 rules for a single employee earning 6 million JPY who contributes 240,000 yen). Payouts also use retirement or pension deductions. Check your savings with the iDeCo tax-saving simulation.

Withdrawal freedom and limits

The biggest real-life difference is when you can withdraw. The new NISA can be sold and cashed out anytime, so it suits any goal: education, housing, or retirement. iDeCo, by contrast, cannot be withdrawn until age 60 in principle, so never overcommit just for the tax break. Keep emergency funds and near-term money outside iDeCo.

Limits differ too: the new NISA allows up to 3.6M yen a year (1.2M tsumitate plus 2.4M growth quota), while iDeCo ranges from 20k to 68k yen a month depending on occupation and workplace pension. From the December 2026 contribution (debited in January 2027), the iDeCo limits rise to 75k yen for the self-employed, 62k yen for employees without a corporate pension, 62k yen minus the corporate pension contribution for those with one, and 54k yen for civil servants (dependent spouses stay at 23k yen).

Which should you prioritize

• Start with the new NISA: its flexibility and lack of account fees make it the easiest first step, especially if you may need the money in the near future.
• iDeCo shines for high earners with spare retirement money: the more income tax you pay, the larger the deduction benefit.
• Low earners paying little tax get almost no deduction benefit, so the flexible new NISA is the rational priority.

In short: if in doubt, start with the new NISA, and add iDeCo if your tax burden is heavy and you can spare money for retirement.

Using both together

You can use the new NISA and iDeCo together to maximize tax benefits. One ideal order:

1. Secure emergency cash (six months to a year of living costs).
2. Contribute a sustainable amount to iDeCo for the income deduction.
3. Invest the rest in the freely withdrawable new NISA.

Over the long run, reinvested tax-free gains compound significantly. See the effect with the compound interest calculator. The younger you start, the longer your runway and the bigger the advantage.

This article is general information only. Tax rules, limits, and eligibility may change. Always confirm actual quotas, savings, and withdrawal conditions with official sources (the FSA, the NTA, the official iDeCo site) or a qualified professional.