iDeCo Tax Saving Simulation

Estimate the yearly and cumulative tax savings from iDeCo contributions, based on your monthly contribution and annual income (in yen).

Input

Enter your monthly contribution, annual income, and years to estimate how much tax the iDeCo income deduction can save you.

Monthly contribution

yen

Annual income (gross)

x10k yen

Used to judge your income tax rate

Occupation type

Reference monthly contribution cap for this type is 23,000 yen

Saving years

years

Result

Yearly tax saving

55,780yen

Income tax saved (yearly)

28,180 yen

Resident tax saved (yearly)

27,600 yen

Cumulative tax saving

1,115,600 yen

Cumulative contributions

5,520,000 yen

Breakdown

Annual contribution	276,000 yen
Taxable income (estimated)	2,330,000 yen
Applied income tax rate	10.0 %
Resident tax rate	10.0 %
Income tax saved (yearly)	28,180 yen
Resident tax saved (yearly)	27,600 yen
Total yearly tax saving	55,780 yen

A rough estimate using representative FY2024 values. Tax-free investment gains and taxation at withdrawal are excluded. Confirm exact figures yourself.

How it works

iDeCo (the Japanese individual defined contribution pension) contributions are fully deductible from taxable income as a small enterprise mutual aid type deduction. So your tax burden is reduced by your marginal income tax rate plus the resident tax rate applied to your yearly contribution.
This tool estimates the yearly saving as your annual contribution times the income tax marginal rate (with the 2.1% reconstruction surtax) plus a 10% resident tax rate, then multiplies by the number of years for the cumulative saving.
The income tax rate is judged from your taxable income, derived from annual income minus the employment income deduction, an estimated social insurance amount (about 15% of income), and the basic deduction of 480000 yen, using progressive rates from 5% to 45%.
Monthly contribution caps differ by occupation. Representative figures are 23000 yen for employees with no corporate pension, 20000 yen with a corporate DC plan, 12000 yen with a defined benefit plan or for public servants, 68000 yen for the self-employed, and 23000 yen for homemakers.
Rates and deductions are rough estimates based on representative FY2024 (Reiwa 6) values. Tax-free investment gains and taxation at withdrawal are not included. Actual amounts vary by income, dependents, deductions, and municipality, so please confirm the exact figures yourself.

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