Kokumin Kenko Hoken Health Insurance — Mandatory for Vietnamese Residents in Japan

KKH premiums in 2026 — how are they calculated?

KKH premiums consist of 4 components + additional taxes, with details varying by ward. The general formula is:

1. Per-capita portion (均等割 — kintouwari): A fixed amount per person, ~40-50k yen/year
2. Income-based portion (所得割 — shotokuwari): 7-10% of taxable income from the previous year
3. Asset-based portion (in some wards): 0.5% of the value of your assets
4. Household portion (平等割 — byōdouwari): ~20-30k yen/household

Example: Tokyo’s Shinjuku Ward (2026):

New arrival with no income in the previous year:

• Kintouwari: ~47,000 yen
• Shotokuwari: 0 (no income)
• Total: ~47,000 yen/year = ~3,900 yen/month

International student earning 100万/year (baito 28h/week):

• Kintouwari: ~47,000 yen
• Shotokuwari: (1,000,000 - 430,000 deduction) × 7.13% = ~40,600 yen
• Total: ~87,600 yen/year = ~7,300 yen/month

IT employee earning 600万/year (if not enrolled in Shakai Hoken):

• Kintouwari: ~47,000 yen
• Shotokuwari: (6,000,000 - 430,000) × 7.13% = ~397,000 yen
• Total: ~444,000 yen/year = ~37,000 yen/month

💡 Reductions: Students may apply for a 70% premium reduction if their previous year’s income was <43 man yen. Submit a "減免申請" at the kuyakusho and bring proof of income.

Registering for KKH — 5 steps

Step 1: Register your juminhyo first

You register for KKH at the kuyakusho in the same ward as the address on your juminhyo. If you do not have a juminhyo yet, complete that registration first using this guide.

Step 2: Get the form at the kuyakusho

• The "国民健康保険" (kokumin kenko hoken) counter — usually on the 1st floor, near the juminhyo counter
• Form: 国民健康保険被保険者資格取得届 (kokumin kenko hoken hihokensha shikaku shutoku todoke)
• English-language versions are available in Tokyo + major cities

Step 3: Fill out the form and submit your documents

Bring:

• Residence card
• Juminhyo (copy)
• My number card (if you have one) — if you do not have one yet, that is OK
• Passport

Step 4: Receive your insurance card

• The "国民健康保険被保険者証" (kokumin kenko hoken hihokensha-shō) — about the size of an ATM card
• Issued at the counter immediately (30 minutes) OR mailed after 1-2 weeks (depending on the ward)
• Valid for: 1-2 years, with automatic renewal as long as you remain a resident

Step 5: Receive your payment slips

• 1-2 months after registration, the kuyakusho sends payment slips (納付書 — nōfusho)
• Divided into 8-10 installments/year (June, 7, 8, 9, 10, 11, 12, 1, 2, 3)
• Pay at:
  • Convenience stores (7-Eleven, FamilyMart, Lawson) — the most convenient option
  • Post offices
  • Automatic bank transfer (口座振替 — kouza furikae) — register once and never worry about remembering the due date

Going to the doctor — how to use your KKH card

When you are healthy: find a "kakaritsuke-i" (かかりつけ医 — primary care doctor)

• Choose a clinic (診療所 — shinryōjo) near your home
• For your first visit, bring your KKH card + residence card + 2,000-3,000 yen for the initial consultation (30% of 7-10k yen)

For minor illnesses: visit a clinic

• Usually open 9:00-12:00 / 15:00-18:00, closed at lunchtime and on Sundays
• Present your KKH card at reception → pay only 30%
• One consultation + 7 days of medication: ~2,000-4,000 yen

For serious illnesses: get a referral to a hospital

• The clinic will write a referral letter (紹介状 — shōkaijō)
• Take the letter + KKH card + residence card to the hospital
• Without a referral letter, you must pay an additional "初診料" (shoshinryō — initial consultation fee) of ~5,000-8,000 yen on top of the 30%

Emergencies: call 119

• Ambulance service is free (unlike in Vietnam)
• Present your KKH card at the hospital
• Emergency treatment at night: there may be an additional 30% nighttime fee, but you are still covered within the 30% copayment

Buying medication: the pharmacy (調剤薬局 — chouzai yakkyoku)

• Take your doctor’s prescription to the pharmacy (usually located next to the clinic)
• Present your KKH card → pay 30% of the medication cost
• Example: 7 days of cold medicine + antibiotics: ~500-1,500 yen

The actual 30% copayment — there is an upper limit

KKH has a gendogaku seido (限度額制度 — monthly medical expense cap): no matter how expensive your treatment is, the 30% you pay is capped based on your income:

Example: Appendicitis surgery costs 600,000 yen

• Without KKH: pay 600,000 yen yourself
• With KKH: 30% = 180,000 yen, but the gendogaku is 57,600 yen → you pay a maximum of 57,600 yen
• Apply for a "限度額適用認定証" (gendogaku tekiyou ninteisho) at the kuyakusho before hospitalization → the hospital reduces the bill directly to 57,600 yen

5 common KKH mistakes

1. Registering late → backdated premiums

• The law requires registration within 14 days of obtaining your juminhyo
• If you register 6 months late, the kuyakusho charges you for 6 months of premiums (even if you did not have a card during that period) + may charge interest

2. Not paying premiums → your card is canceled

• After missing payments for 2-3 installments: your card is changed to a "短期証" (tanki-shō — short-term card valid for 1-3 months)
• After 6 months without payment: your card is changed to a "資格証明書" (shikaku shomeisho) — you must pay 100% of medical costs upfront and then apply for a 70% reimbursement
• After 1 year without payment: your visa renewal may be affected

3. Not reporting a change of address

• Your card becomes invalid when the system detects that your address does not match your juminhyo
• You must go to the new kuyakusho to have your card changed

4. Failing to report a lost card

• Someone who finds it could use it to receive medical treatment, leaving you responsible for the charges and potentially exposing you to criminal liability
• Report the loss to the kuyakusho within 24h; they will deactivate the old card and issue a new one (500 yen fee)

5. Returning to Vietnam without canceling KKH

• If you do not cancel it, you will continue to be charged premiums + accumulate debt
• If you return to Japan later, you will be billed for the outstanding premiums
• Before flying: go to the kuyakusho, submit the "喪失届" (sōshitsu todoke — loss-of-eligibility notification), and return your card

Tips for saving on KKH premiums

1. Apply for a reduction

• Low income (<43 man/year for students) → 70% reduction
• Sudden job loss → apply for a reduction based on your expected income
• Submit the "減免申請書" at the kuyakusho, along with proof of income

2. Apply for a "限度額適用認定証" (gendogaku card)

• If you know you will be hospitalized / undergo major surgery
• Present this card → the hospital automatically reduces your bill to the upper limit
• You do not have to pay a large amount upfront

3. Visit a clinic instead of a hospital

• Clinic: 30% of 3-5k yen = 1-2k yen
• Hospital: 30% of 8-15k yen = 3-5k yen (plus the shoshinryō fee + longer waits)
• Clinics will refer you to a hospital only when truly necessary

4. Generic medication (後発医薬品 — kouhatsu iyakuhin)

• When the doctor asks "generic OK?" → answer "OK, onegaishimasu"
• 30-50% cheaper than brand-name medication, with equivalent quality

5. Free annual health checkups

• The kuyakusho / your company / school usually offers 1 free checkup per year
• Blood tests, X-rays, urine tests, and heart examinations — early detection can save you money later

Summary

Kokumin Kenko Hoken is mandatory for all residents of Japan ≥3 months. Premiums are 1,500-3,000 yen/month for international students, it covers 70% of medical expenses, and there is a monthly income-based upper limit. Register at the kuyakusho within 14 days of obtaining your juminhyo, then pay via convenience store / post office / automatic bank transfer. Failure to pay = accumulated debt and possible problems with visa renewal. Before returning to Vietnam, remember to cancel your KKH to avoid backdated charges.

KKH comes together with nenkin pension — both can be registered at the kuyakusho at the same time. Finished your moving-in procedures? Open a Yuucho bank account to set up automatic payments for your recurring insurance premiums.

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