Japan NISA Calculator: Tax-Free Investment Growth
Estimate what a Japanese NISA grows to from a starting balance plus regular monthly contributions — Japan's tax-free investment account, where gains and dividends are exempt from the usual ~20% investment tax.
Adjust the inputs and select Calculate for a full breakdown.
Year-by-year growth schedule
Compare Common Scenarios
How the numbers shift across typical situations for this calculator:
| Scenario | Future value | Total contributions | Total interest earned |
|---|---|---|---|
| ¥1M + ¥50k/mo · 5% · 10yr | $9,411,123.47 | $7,000,000.00 | $2,411,123.47 |
| ¥0 + ¥30k/mo · 5% · 20yr | $12,331,010.06 | $7,200,000.00 | $5,131,010.06 |
| ¥3M + ¥100k/mo · 5% · 15yr | $33,070,006.18 | $21,000,000.00 | $12,070,006.18 |
| ¥500k + ¥20k/mo · 6% · 25yr | $16,092,364.15 | $6,500,000.00 | $9,592,364.15 |
How This Calculator Works
Enter your current NISA balance, monthly contribution, the return you expect, and the years invested. The calculator compounds the balance monthly and shows the projected value and how much is tax-free growth. Inside a NISA, capital gains and dividends are exempt from tax — versus the roughly 20% tax on investment income in a regular taxable account.
The Formula
Future Value with Regular Contributions
P = starting amount, PMT = monthly contribution, r = monthly rate (annual ÷ 12), n = number of months
Worked Example
A ¥1,000,000 balance plus ¥50,000 a month for 10 years at 5% grows to about ¥9,411,123 — with roughly ¥2,411,123 of that being tax-free growth. NISA (Nippon Individual Savings Account) is Japan's tax-advantaged investment scheme, modelled on the UK ISA. Investment gains and dividends earned inside a NISA are completely tax-free, whereas gains in an ordinary brokerage (tokutei) account are taxed at about 20% (20.315% including the surtax) — so the NISA shelter materially boosts long-run net returns.
Key Insight
NISA is the centrepiece of Japan's push to move household savings from cash into investments, and the 'new NISA' that began in 2024 made it far more powerful. The core benefit is the tax exemption: capital gains and dividends inside a NISA are entirely tax-free, compared with the roughly 20.315% tax (including the special reconstruction surtax) levied on investment income in a normal taxable (tokutei or general) account — over years, sheltering that tax meaningfully increases compounding. The new NISA has two contribution frames that can be used together: the 'tsumitate' (accumulation) frame for regular contributions into eligible low-cost funds, and the 'growth' frame for a wider range of investments, with substantially higher annual and lifetime investment limits than the old NISA, and — importantly — the new NISA is permanent and the tax-free holding period is indefinite (the old NISA had time limits). Key points this estimate omits: the annual and lifetime investment caps (the lifetime limit is measured by amount invested, and selling frees up room to reinvest the following year), and fund fees, which compound against you over decades, so low-cost index funds are favoured. NISA is generally for residents of Japan and held at one provider per year. For long-horizon investors, maximising NISA before taxable accounts is usually optimal, since the tax-free growth is the most valuable space. This is a constant-return estimate (real markets vary), but every yen of growth shown is free of the ~20% investment tax — which is the whole point of using a NISA rather than a regular brokerage account.
The two compartments and the 18M yen lifetime cap
The 2024 'new NISA' merged the old Tsumitate and General NISAs into a single permanent account with two annual investment quotas you can use in parallel: the Tsumitate (accumulation) quota of ¥1.2M/year, restricted to a curated list of low-cost diversified funds approved for long-term saving; and the Growth quota of ¥2.4M/year, open to a much wider selection of individual stocks, ETFs, REITs, and active funds.
The combined annual cap is therefore ¥3.6M, and there is a lifetime investment limit of ¥18M (Growth alone is capped at ¥12M of the ¥18M total; Tsumitate alone can occupy the full ¥18M). Once the lifetime cap is reached, you can't add new money — but the tax-free status of what's already inside is permanent.
Selling holdings restores lifetime room: if you sell ¥1M of NISA holdings (measured at acquisition cost, not market value), ¥1M of lifetime room becomes available for new contributions the following year. This is a major change from the old NISA, which had a fixed time limit and no restoration.
NISA vs iDeCo: which one and how much
iDeCo offers a deduction on contributions (reducing income tax and resident tax now) plus tax-free growth and favourable withdrawal taxation, in exchange for locking the money until age 60. NISA offers no upfront deduction but tax-free growth and full liquidity. They serve different needs.
The optimal Japanese saver uses both: max iDeCo for retirement-locked money (Category 2 employees with corporate pension: ¥12k/mo; without: ¥23k/mo; Category 1 self-employed: ¥68k/mo; Category 3 dependent spouses: ¥23k/mo) — capturing the income-tax deduction worth roughly 20–55% of every yen contributed depending on bracket — then funnel everything else into NISA for tax-free growth without lock-up.
For someone whose marginal tax rate is below 10% (e.g. part-time workers, dependent spouses with low income), the iDeCo deduction is worth little and the lock-up is the binding constraint. In those cases, NISA alone is the cleaner choice.
Funding NISA for a child's future and the kids-NISA proposal
Under current rules the new NISA is available only to residents of Japan aged 18+. A 'Kids NISA' (こどもNISA) for minors has been formally proposed by the FSA for introduction from 2026, mirroring the old Junior NISA but permanent.
Meanwhile, parents commonly use their own ¥18M NISA capacity for the child's future — investing ¥30,000 to ¥50,000/month from birth so that by age 18 the corpus is substantial. At ¥30,000/month for 18 years at 5% return, the corpus reaches roughly ¥10.5M; at ¥50,000/month, roughly ¥17.5M, very close to the lifetime cap.
The tax-free shelter compounds dramatically over 18 years: a standard taxable account would surrender approximately ¥3M of the gains to the 20.315% investment-income tax over the same period. The NISA shelter is the single largest tax saving available to Japanese retail investors.
Projected NISA value by monthly contribution and horizon
Monthly contribution, compounded monthly at the assumed annual return. Higher monthly amounts approach or exceed the ¥18M lifetime cap.
| Monthly contribution | 10 years at 5% | 20 years at 5% | 30 years at 5% |
|---|---|---|---|
| ¥30,000 | ¥4,658,469 | ¥12,330,694 | ¥24,968,213 |
| ¥50,000 | ¥7,764,114 | ¥20,551,156 | ¥41,613,689 |
| ¥83,000 (~ max Tsumitate alone) | ¥12,888,429 | ¥34,114,919 | ¥69,078,723 |
| ¥100,000 | ¥15,528,228 | ¥41,102,313 | ¥83,227,377 |
Lifetime contribution cap is ¥18,000,000 — combinations above approach or exceed it. The numbers shown are tax-free under NISA versus a roughly 20.315% drag in a regular taxable account.
Frequently Asked Questions
How is NISA growth calculated?
Your balance and monthly contributions compound at the expected return (annual rate ÷ 12 per month). ¥1,000,000 plus ¥50,000/month for 10 years at 5% grows to about ¥9,411,123, with roughly ¥2,411,123 of that being tax-free growth — before fund fees.
Why is a NISA better than a regular brokerage account?
Because of the tax exemption. Capital gains and dividends inside a NISA are completely tax-free, whereas investment income in an ordinary taxable (tokutei) account is taxed at about 20.315% (including the reconstruction surtax). Sheltering that tax over years materially boosts net compounding.
What changed with the new NISA in 2024?
The new NISA is permanent with an indefinite tax-free holding period (the old NISA had time limits), has much higher annual and lifetime investment limits, and combines two frames — 'tsumitate' (regular accumulation into eligible funds) and 'growth' (a wider investment range) — usable together. It made NISA far more powerful for long-term investing.
Are there limits on how much I can invest?
Yes — the new NISA has annual contribution limits and an overall lifetime investment limit (measured by amount invested). Selling holdings frees up lifetime room to reinvest the following year. This calculator doesn't enforce the limits, so confirm your contributions fit the current caps.
Should I use a NISA before a regular account?
For long-horizon investing, usually yes — the tax-free growth is the most valuable space, so maximising NISA before taxable accounts is generally optimal. Favour low-cost index funds (fees compound against you over decades), and note NISA is for Japan residents, held at one provider per year.
References & Authoritative Sources
- FSA — Financial Services Agency of Japan — New NISA (2024) — official scheme guide · consulted May 31, 2026 · Statutory regulator — NISA framework, growth and tsumitate quotas, lifetime limit
- National Tax Agency of Japan — NISA — tax exemption rules · consulted May 31, 2026 · Tax administration — exemption of dividends and capital gains within a NISA
- Income Tax Act (Shotokuzeiho) — Statutory basis for NISA tax-exempt accounts · consulted May 31, 2026 · e-Gov — full statutory text including the NISA provisions
Related Calculators
Methodology & Review
The future value compounds a starting balance and a fixed monthly contribution at the annual return, compounded monthly. It assumes deposits at month end and a constant return; it does not enforce the annual or lifetime NISA investment limits or model fund fees.
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