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Japanese Retirement System: iDeCo, NISA, and Kosei Nenkin Explained

2024-08-05

Educational content only. Rules and tax laws change over time; verify official sources.

Japan's retirement system combines a robust public pension (kosei nenkin) with two powerful tax-advantaged accounts - iDeCo and NISA. Understanding all three is essential for anyone building wealth in Japan, where the average monthly public pension is just ¥145,000.

Pillar 1: Kosei Nenkin (Employees' Pension Insurance)

If you work for a company in Japan, you're enrolled in kosei nenkin (厚生年金). Here's how it works:

  • Contribution rate: 18.3% of salary (9.15% each from employee and employer)
  • Pension age: 65 (gradually raised from 60)
  • Average monthly benefit: approximately ¥145,000/month (~$970)
  • Maximum benefit: approximately ¥220,000/month for 40+ year contributors
  • Includes kokumin nenkin (basic pension): about ¥65,000/month base

On a salary of ¥5 million/year (~$33,500), kosei nenkin contributions total about ¥915,000/year split between you and your employer. After 35+ years, expect roughly ¥150,000-¥180,000/month combined pension.

Pillar 2: iDeCo (Individual Defined Contribution Pension)

iDeCo (個人型確定拠出年金) is Japan's most powerful tax-advantaged retirement account:

  • Contribution limit for company employees: ¥23,000/month (¥276,000/year) if employer has no corporate pension; ¥12,000-¥20,000/month otherwise
  • Self-employed: Up to ¥68,000/month (¥816,000/year)
  • Tax deduction: 100% of contributions are tax-deductible from income
  • Growth: Completely tax-free while invested
  • Withdrawal: Available from age 60 (must contribute for 10+ years)

For an employee in the 20% income tax bracket contributing ¥23,000/month, the annual tax savings are approximately ¥55,200 in income tax plus ¥27,600 in resident tax = ¥82,800/year. Over a 30-year career, that's ¥2.48 million in tax savings alone.

Pillar 3: NISA (Nippon Individual Savings Account)

The new NISA system (launched January 2024) dramatically expanded tax-free investing in Japan:

  • Tsumitate (accumulation) NISA: ¥1.2 million/year for index funds and approved investment trusts
  • Growth NISA: ¥2.4 million/year for individual stocks and broader funds
  • Lifetime limit: ¥18 million total (¥3.6M/year combined maximum)
  • Tax benefit: ALL gains and dividends are completely tax-free forever
  • No time limit: Hold indefinitely (old NISA had 5/20-year limits)

The new NISA is a game-changer. ¥18 million invested at 5% annual returns grows to approximately ¥47 million over 20 years - all tax-free. Without NISA, you'd pay 20.315% tax on those ¥29 million in gains (approximately ¥5.9 million in tax).

Optimal Japanese Investment Order

  1. iDeCo (up to ¥23,000/month): Immediate tax deduction makes this the highest-priority account
  2. Tsumitate NISA (¥100,000/month): Tax-free growth with flexible withdrawals - no age restriction
  3. Growth NISA (¥200,000/month): Additional tax-free capacity for stocks and broader funds
  4. Taxable brokerage (特定口座): After NISA/iDeCo limits are maxed

Popular Funds in Japan

  • eMAXIS Slim All Country (オルカン): The most popular NISA fund - global stock index with very low fees (0.05775%)
  • eMAXIS Slim S&P500: US market exposure, second most popular
  • eMAXIS Slim TOPIX: Japanese domestic stock index

Most Japanese FIRE investors use a simple 70-80% global stocks / 20-30% bonds allocation through these low-cost index funds.

Kosei Nenkin + iDeCo + NISA Together

For a company employee earning ¥5M/year, maximizing all accounts:

  • Kosei nenkin: ¥457,500/year (mandatory, matched by employer)
  • iDeCo: ¥276,000/year (tax-deductible)
  • NISA: Up to ¥3,600,000/year (tax-free gains)

That's ¥4.33 million/year in tax-advantaged savings - 87% of gross salary. Realistically, most workers prioritize iDeCo + Tsumitate NISA within their budget. For early retirement strategies, see our FIRE in Japan guide.

Calculate Your Japanese Retirement Strategy

Use our free retirement calculator to see how kosei nenkin, iDeCo, and NISA contributions work together to determine your retirement timeline.

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Apply this framework to your own situation.

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