Eligibility, contribution limits, the three tax advantages, product menus, fees, withdrawal restrictions, and upcoming changes.
iDeCo is a private defined-contribution pension whose contributions are generally fully deductible from income and whose growth is tax-deferred, in exchange for locking the money until eligible retirement age; limits depend on employment and employer-pension coverage.
iDeCo (個人型確定拠出年金) is a private defined-contribution pension with three tax advantages. First, contributions are generally fully deductible from your income, so they reduce this year’s income tax and resident tax — an immediate, certain benefit that scales with your marginal rate. Second, investment returns accumulate without current tax (tax-deferred). Third, retirement or pension deductions may apply when you eventually receive the money.
This up-front deduction is what can make iDeCo outrank NISA for higher earners: NISA’s benefit is tax-free growth, while iDeCo adds a certain deduction today. The trade-off is liquidity, discussed below.
Most working-age residents can join, but contribution limits depend on your pension category — self-employed (Category 1), employees (Category 2), and dependent spouses (Category 3) have different ceilings, and an employer defined-contribution or defined-benefit plan can reduce your iDeCo room. Minimum contributions are normally ¥5,000 per month in ¥1,000 increments.
You invest from the plan administrator’s menu, typically low-cost index funds plus target-date and principal-protected options. Watch fees: iDeCo carries account-management and administrative charges on top of fund expenses, so a low-cost administrator and low-cost funds matter over a multi-decade horizon.
The defining constraint is lock-up: iDeCo funds are generally inaccessible until eligible retirement age, and you cannot make an emergency withdrawal. This is why iDeCo suits money you are confident you will not need before retirement, and why NISA — fully flexible — usually comes first for general saving. Employer-plan interactions and receipt taxation also deserve attention: how you take the money (lump sum vs pension) affects the applicable deductions.
Rules are changing: reforms scheduled from December 2026 broaden some contribution limits. Anyone enrolling around that date should verify the implemented figures rather than relying on pre-change numbers, and confirm how the changes interact with any employer plan.
Brokerage (NISA/iDeCo) · Rakuten Securities
A leading low-cost brokerage for NISA and index-fund investing, integrated with Rakuten points and Rakuten Bank.
Fees: Many domestic funds and trades are low- or no-commission — verify current fee schedule.
Brokerage (NISA/iDeCo) · SBI Securities
Japan’s largest online brokerage by accounts, with a very broad low-cost fund lineup and full NISA/iDeCo support.
Fees: Many trades and funds are low- or no-commission — verify current fee schedule.
Brokerage (NISA/iDeCo) · Monex
An established online brokerage often chosen for US-stock access and research tools, with NISA and iDeCo support.
Fees: Commissions vary by product; some funds/trades are low-cost — verify current schedule.
They solve different problems. NISA is flexible: tax-free growth and you can withdraw anytime, making it the usual first choice. iDeCo gives a larger up-front tax break (contributions cut your taxable income) but locks money until age 60 and suits committed retirement saving. Many use NISA first for flexibility, then add iDeCo for the deduction if they are confident they will not need the money before 60. If you may leave Japan, iDeCo’s lock-up is a bigger drawback.