Dependant "Income Wall" Simulator｜Visualizing the "valley" where working more cuts your take-home pay
Part-time and casual wages run into several tax and social-insurance "walls." Enter an annual income and the tool calculates your own income tax, residence tax and social-insurance premiums plus your take-home pay, and plots on a graph how your take-home pay moves as your income rises (the "valley" where working more loses money). It also reflects the FY2026 reform, which raised the income-tax wall from ¥1.03M to about ¥1.60M. No sign-up required; your input is not transmitted and is calculated entirely on your device (rough estimate).
* The "¥1.06M wall" is the line at which you enroll in social insurance under certain conditions — 20+ hours a week, ¥88,000+ a month, an employer with 51+ employees, etc. If you are not covered, the "¥1.30M wall" is where you leave your spouse's dependant (social-insurance) status.
Quick reference to the dependant "walls" (FY2026, reform reflected)
| About ¥1.00M | The residence-tax wall (for you). Above this, you start to owe residence tax (roughly ¥980,000–¥1.00M depending on the municipality). |
|---|---|
| ¥1.06M | The social-insurance wall (for you). At workplaces meeting certain conditions such as 51+ employees, once you exceed ¥1.06M (¥88,000 a month) you enroll in social insurance yourself. Your take-home pay drops a notch. |
| ¥1.30M | The social-insurance wall (for you). Even if you are not covered above, once you exceed ¥1.30M you leave your spouse's dependant (social-insurance) status and must enroll on your own. |
| About ¥1.60M | The income-tax wall (for you). It was ¥1.03M before the reform, but with the higher basic deduction and employment-income deduction, you now owe no income tax up to about ¥1.60M. |
| ¥1.50M / ¥2.01M | The spousal (special) deduction wall (on the spouse's side). Up to ¥1.50M of your income, the spouse claims the full spousal special deduction; above that it phases down and disappears at ¥2.01M. |
* This tool is a rough estimate for general information only, not tax or social-insurance advice. Your social-insurance premiums are estimated at about 15% of income after enrollment (in reality they are set by your standard monthly remuneration and the premium rates). Residence tax is estimated as a 10% income levy plus a ¥5,000 per-capita levy and the tax-exemption threshold. It does not include the spouse's deductions or household-wide optimization. For an accurate determination, please check with your employer, the pension office, your municipality, or a tax accountant.
Related pages
- Tax Reform Simulator (how much your tax changes under the reform)
- Employees' side jobs and taxes / Tax calculation tools
Sources / references: National Tax Agency — FY2026 reform (in Japanese), Ministry of Health, Labour and Welfare — expanded social-insurance coverage (in Japanese) (please check each official site for the latest details).