The Basics of Investment Taxation in Japan

In Japan, investment gains are taxed at 20.315% (15.315% income tax + 5% resident tax). On a 100 man-yen profit, only about 79.7 man-yen remains after tax. Over the long term, this tax burden significantly erodes the compounding effect.

For further reading, introductory books on the new NISA system can help you understand how to use the Tsumitate and Growth investment frames effectively.

For example, investing 100 man-yen at 5% annual return for 30 years yields approximately 432 man-yen tax-free, but only about 340 man-yen if gains are taxed at 20.315% each year. The difference of roughly 92 man-yen is caused by taxation alone.

Overview and Strategies for the NISA System

The new NISA, revamped in 2024, is a system that makes investment gains completely tax-free. It offers two frames: the Tsumitate (regular investment) frame with an annual limit of 120 man-yen, and the Growth investment frame with an annual limit of 240 man-yen, for a combined annual investment capacity of 360 man-yen. The lifetime tax-free holding limit is 1,800 man-yen, and the tax-free period is unlimited.

  • Tsumitate investment frame: Eligible products are low-cost investment trusts screened by Japan's Financial Services Agency. Ideal for monthly dollar-cost averaging, this is the best starting point for beginners.
  • Growth investment frame: Covers individual stocks and a broader range of investment trusts. Useful for lump-sum investments or products not available in the Tsumitate frame.
  • When you sell, the tax-free allowance is restored the following year, enabling flexible use of funds for life events.

How iDeCo Works - Three Layers of Tax Benefits

iDeCo (individual-type Defined Contribution pension plan) is a tax-advantaged system specifically designed for retirement savings. It provides tax benefits at three stages: contribution, accumulation, and withdrawal.

  • Tax deduction on contributions: The full amount of contributions is deductible from taxable income. A salaried worker earning 500 man-yen annually who contributes 2.3 man-yen per month (27.6 man-yen per year) saves roughly 5.5 man-yen in combined income and resident taxes each year - about 165 man-yen over 30 years.
  • Tax-free accumulation: Like NISA, investment gains within iDeCo are exempt from the 20.315% tax.
  • Tax-advantaged withdrawals: Lump-sum withdrawals qualify for the retirement income deduction, and annuity-style withdrawals qualify for the public pension income deduction. With 30 years of equivalent service, up to 1,500 man-yen can be received tax-free.

Choosing Between NISA and iDeCo, and Tax-Loss Offsetting

NISA offers high liquidity - you can sell and withdraw at any time. iDeCo, on the other hand, locks funds until age 60 but provides an immediate tax deduction on contributions. An efficient priority is to first capture iDeCo's income deduction benefit, then direct surplus funds to NISA.

Note that losses within a NISA account cannot be used for tax-loss offsetting. In a taxable account, losses on one holding can offset gains on another, reducing your tax bill. Furthermore, if losses exceed gains, the excess can be carried forward for up to three years. Understanding this distinction is essential when using NISA and taxable accounts together.

Books explaining iDeCo's tax benefits can help you understand the income deduction mechanism and calculate your potential savings.