National Health Insurance (Kokuho) Calculator

When you leave a Japanese company, you typically have 14 days to enrol in National Health Insurance (kokumin kenko hoken, 国民健康保険) — also called NHI or kokuho. Premiums are based on last year's income, so they can be a shock if you just resigned. This tool estimates your annual and monthly cost.

Household members

Member 1

Last year's income (JPY)

Age group

Estimated NHI premium

NHI is split across 10 monthly payments (June–March). The monthly figure below assumes 12-month spread.

Annual total

¥433,267/year

Effective rate 10.8%

Monthly equivalent

¥36,105/month

Medical (max 670,000): ¥315,707
Elderly support (max 260,000): ¥117,560
Annual total: ¥433,267

Estimate based on Shinjuku Ward FY2026 rates. Other municipalities differ by roughly ±10%. Premium reductions (low-income, job loss) are not applied. Premiums for fiscal year (April–March) are determined from previous calendar year's income.

How NHI is calculated

NHI premium has three components, each with an income-proportional part and a flat-per-member part:

Medical: 7.51% of (income − 430,000 JPY basic deduction) + 47,600 JPY/person, capped at 670,000 JPY/household
Elderly support: 2.80% + 17,600 JPY/person, capped at 260,000 JPY
Long-term care (only for ages 40–64): 2.21% + 17,400 JPY/person, capped at 170,000 JPY

Rates differ slightly by municipality. This calculator uses Shinjuku Ward (Tokyo) FY2026 rates, which are roughly representative of Tokyo's 23 wards. Your actual ward may charge ±10%.

FAQ

Q. NHI vs Voluntary Continuation (Nin-i Keizoku) — which is cheaper?: After leaving a company, you can either join NHI or continue your old employer-based health insurance via nin-i keizoku(任意継続) for up to 2 years. Voluntary continuation premium = 2 × your previous employee share (because you also pay the employer share). The cheaper option depends on last year's income vs. the standard monthly remuneration cap. For high-earners, voluntary continuation is often cheaper. For low-to-mid earners, NHI is usually cheaper. Compare both before deciding.
Q. Why is NHI based on LAST year's income?: NHI premiums for fiscal year (April–March) are calculated from the previous calendar year's income reported on your tax return or company-issued gensen choshu hyo. So if you earned a lot last year and have low income now, you still pay based on last year. Conversely, your first NHI year may be cheaper than expected if you just arrived in Japan with low Japan-source income last year.
Q. What if I cannot afford it?: Apply for a premium reduction (軽減・減免) at your ward office — typically 7/5/2-tier reduction is available for low-income households. Job loss for a non-disqualifying reason (company bankruptcy, layoff) gives you a major reduction (your income for premium calculation is treated as 30% of actual). Do not skip enrolment — premiums accrue retroactively.
Q. Is dental and prescription covered?: Yes — NHI covers 70% of medical, dental, and prescription costs, with you paying the remaining 30%. Same coverage as company health insurance. The High-Cost Medical Care benefit also caps your monthly out-of-pocket (typically ~80,000 JPY/month for average earners).
Q. Do I need to enrol if my visa is short?: Yes. Anyone with a residence card valid for 3+ months must enrol. There is no opt-out. Failure to enrol can result in retroactive premiums of up to 2 years and complications when renewing your visa.

Estimate for FY2026 / Reiwa 8 using Shinjuku Ward rates. Premium reductions for low income or job loss are not applied. Caps apply per household. Spouses and dependents add per-person flat amounts; income-proportional premium is calculated on each member's income separately.