Japan's new NISA (Nippon Individual Savings Account), launched January 1, 2024, offers a generous lifetime contribution cap of ¥18,000,000 — but the structure has a quirk that catches aggressive savers off-guard in year 3.
The two buckets
- Tsumitate (accumulation) bucket: ¥1.2M/year max via regulated funds (long-term investment focus).
- Seicho (growth) bucket: ¥2.4M/year max, broader asset selection including individual stocks.
- Combined cap: ¥3.6M/year.
- Lifetime cap: ¥18M total (across both buckets combined).
The year-3 trap
If you maxed out the full ¥3.6M/year in 2024 and 2025, you've contributed ¥7.2M and have ¥10.8M headroom. Looks fine — but within the ¥18M cap, the growth bucket alone is limited to ¥12M lifetime. If your ¥2.4M/year growth contributions have been the main driver, you've already consumed ¥4.8M of the ¥12M growth cap. Another 3 years at that pace and you're maxed out by year 6.
Why this matters
Once you hit the growth-bucket cap, you can still add to tsumitate — but many Japanese investors prefer the growth bucket for ETFs like VT, VOO, or individual stocks. Pre-planning your contribution split matters.
Selling creates new room — with a 1-year delay
Unlike the US Roth IRA, selling inside new NISA restores contribution room — but not immediately. The "return" happens in the next calendar year. So selling a fund in 2026 frees up that acquisition cost for 2027 contributions. This turns new NISA into a genuinely dynamic tax shelter.
iDeCo alongside NISA
iDeCo remains valuable for the income-tax deduction (NISA contributions are not deductible — only gains are tax-free). The 2024-2025 iDeCo limit raise (to ¥62,000/month for self-employed, ¥23,000 for DC employees) is an easy top-up on top of NISA.
What to do
1. Check your growth bucket usage on Rakuten/SBI/Monex dashboards. 2. If you're under ¥12M growth cap and under age 40, consider shifting new contributions 40/60 tsumitate/growth to balance longer-term room. 3. Use our retirement projection tool with the JPY ¥18M cap to see when you'll cap out.