iDeCo Calculator (個人型確定拠出年金)

iDeCo (個人型確定拠出年金, individual Defined Contribution pension) is a Japanese private pension you fund yourself, on top of your public pension. You choose the monthly amount within your category's limit, invest it in funds you select, and every yen you contribute is fully deductible from your taxable income for that year, the 小規模企業共済等掛金控除 (small business mutual aid premium deduction). That lowers both your national income tax and next year's resident tax. Growth inside the account is tax-free while invested, and withdrawals from age 60 are taxed favorably through the same retirement income deduction mechanic used for lump-sum severance payouts, though usually you can't touch the money before then.

It depends entirely on your employment category. As of mid-2026: self-employed/freelance is ¥68,000/month, a company employee with no workplace pension is ¥23,000/month, a company employee with a workplace Defined Contribution plan is ¥20,000/month (further limited if your employer's own DC contribution plus your iDeCo pushes the combined total past ¥55,000/month), a company employee with a Defined Benefit plan or a civil servant is ¥12,000/month, and a homemaker/dependent spouse (第3号被保険者) is ¥23,000/month. Pick your category in the calculator above to see your actual cap.

Yes, confirmed. Effective for December 2026 contributions (first reflected in the January 2027 debit), most categories move toward a unified ¥62,000/month combined ceiling: self-employed rises to ¥75,000/month, company employees with no workplace pension rise from ¥23,000 to ¥62,000/month, and the old iDeCo-specific sub-caps for workplace DC/DB participants and civil servants (¥20,000 and ¥12,000) are abolished in favor of a combined ¥62,000/month limit alongside employer contributions. The homemaker/dependent spouse limit stays at ¥23,000/month, unchanged. This calculator defaults to the CURRENT limits that apply to contributions made today, since the reform hasn't taken effect yet.

Your relief rate is (national income tax saved + resident tax saved) ÷ your annual contribution. Resident tax saves a flat ~10% of whatever taxable income the contribution removes. National tax saves at your MARGINAL bracket rate (plus the 2.1% reconstruction surtax) on that same slice of income. If your contribution is large enough to push part of your taxable income down into a LOWER bracket, part of the deduction saves at the lower rate and part at the higher rate, which blends your effective relief rate to somewhere between the two, rather than a single flat percentage.

No, deliberately. This tool focuses on the CONTRIBUTION-side relief, the headline reason most people start iDeCo, using the same real tax engine as this site's other Japan calculators. Investment growth depends on your fund choices and markets over decades, which isn't something a tax calculator should guess at. Withdrawal-side tax at age 60+ uses the retirement income deduction mechanic modeled in this site's Japan Retirement Payout Tax Calculator (退職金), worth checking separately once you're closer to drawing the money out.

Yes, you can generally change your monthly contribution amount once a year, and your category-based limit updates automatically if your employment situation changes, for example moving from a company with no workplace pension to one with a Defined Contribution plan, or from employee to self-employed. Notify your iDeCo provider (運営管理機関) when your employment status changes so your account and limit stay correct, since contributing above your actual limit can create administrative problems.

It derives your taxable income from salary alone using 2026 employment income deduction, social insurance, and basic deduction figures, subtracts your annual iDeCo contribution, and recomputes national income tax and resident tax at the lower figure using the same NTA bracket schedule. Monthly contribution limits reflect the CURRENT figures verified via multiple 2026-dated iDeCo provider sources, with the confirmed December 2026 reform noted separately. It assumes a salary-only taxpayer with no other significant deductions. This is a planning estimate, not tax or investment advice: confirm your exact limit and figures with your iDeCo provider or a tax professional.