Japan self-employed net income calculator (個人事業主)
Your net income as a Japanese sole proprietor is business income minus the flat national pension premium, national income tax after the 650,000 yen blue-return deduction and the basic deduction, and resident tax at 10%.
Worked example: with Annual business income after expenses of 6,000,000, this model computes Net income / year 4,820,818.67. See the full breakdown.
⚠ Illustrative rates Updated for 2026 · sources checked 2026-08-22
How 個人事業主 in Japan is calculated
Filing a blue return is the highest-return administrative decision a Japanese sole proprietor makes. Keeping double-entry books and submitting 青色申告 electronically buys a flat 650,000 yen deduction that a white return does not receive, and because resident tax and national health insurance premiums are all computed from the same reduced figure, the saving compounds across three separate charges.
The national pension works the other way. It is a flat monthly premium — 17,920 yen in 2026 — with no relationship to income at all, which makes it a heavy fixed cost in a thin year and an afterthought in a good one. National health insurance, set by your municipality rather than nationally, sits alongside it and is the largest thing this page cannot compute for you.
Worked example
| Annual business income after expenses (JPY) | 6000000 |
|---|---|
| National pension ✓ | 215040 |
| After Blue Return ✓ | 5350000 |
| Taxable Income ✓ | 4554960 |
| Income tax (incl. surtax) ✓ | 493645.33 |
| Resident tax (10%) ✓ | 470496 |
| Net income / year ✓ | 4820818.67 |
Every row is computed by the engine from the inputs above. Rows marked ✓ are additionally pinned by a published self-test vector.
Frequently asked questions
How much is the blue return deduction worth?
A flat 650,000 yen off business income for a sole proprietor keeping double-entry books and filing electronically. It reduces national income tax, resident tax and the income figure used for national health insurance.
How much is the national pension premium in 2026?
17,920 yen a month, or 215,040 yen for the year. It is the same amount regardless of income, which is why it weighs so heavily on a low-income year.
Does this include national health insurance?
No. 国民健康保険 is set by your municipality and varies substantially across the country, so it cannot be computed nationally. It is often the second largest deduction after income tax.
Sources
- 国税庁 — 所得税の税率および青色申告特別控除 · checked 2026-08-22
- 2026年度（令和8年度）国民年金保険料 月額17,920円 · checked 2026-08-22
Estimate. Not tax advice. The rates in this calculator are illustrative: they reproduce the shape of the charge through 3 self-test cases, but they are not the official schedule, so the amount shown will not match your bill. Use the official source above for that.
Check the arithmetic yourself: how this calculator is verified — the formula behind every derived value, the 3 test cases the engine reproduces, and what the badge does and does not claim. Also available as machine-readable JSON.
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