アメリカの401(k)の仕組み：2026年ガイド
401(k)の全て：拠出、2026年限度額。
401(k)とは
401(k)は米国最人気の退職金プラン。2026年限度$23,500。
2026年拠出限度
| Category | 2026 |
|---|---|
| Employee | $23,500 |
| Catch-up (50+) | $7,500 |
| Total | $31,000 |
| Combined | $70,000 |
Employer match
Typical match: 50% of contributions up to 6% of salary. Earn $60,000, contribute 6% ($3,600), employer adds $1,800 = instant 50% return. ALWAYS contribute up to max match.
Traditional vs Roth 401(k)
| Traditional | Roth | |
|---|---|---|
| Contributions | Pre-tax | Post-tax |
| Withdrawal | Taxed as income | Tax-free |
Investment options
S&P 500 index funds (recommended, ~10% historical), target-date funds, bond funds, company stock (max 10-15%).
Early withdrawal
Before 59½: 10% penalty + taxes. Exceptions: 401(k) loan ($50K max), hardship, rule of 55, SEPP.
Maximizing strategies
- Contribute up to employer match
- Increase 1% annually
- Low-cost index funds
- Consider Roth if future income will be higher
Free tools
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How much should I contribute?
At minimum, up to employer match. Ideally $23,500 (2026 max). If not possible, increase 1% annually.
Traditional or Roth?
High current income → Traditional. Higher future income → Roth. Many recommend 50/50.
Can I withdraw before 59½?
Yes, with 10% penalty + taxes. Exceptions: 401(k) loan, hardship, rule of 55.
What if I change jobs?
Options: leave it, rollover to IRA (recommended), transfer to new 401(k), or withdraw (worst).
How much at retirement?
$500/month × 30 years at 10% = ~$1.13M. Use our 401(k) calculator.
401(k) or IRA?
Complementary. 401(k) has higher limits and match. IRA has more options. Ideally, both.