Insurance料の計算

Detailed explanation of Insurance料の計算 based on official information from 厚生労働省・日本年金機構. Consumption Tax Handling

Published: January 12, 2026

Title: A Comprehensive Guide to Japan's Social Insurance System

1. Overview

Japan's social insurance system is a comprehensive, mandatory framework designed to provide a social safety net for all residents. It is a cornerstone of the country's welfare state, ensuring protection against life's major risks such as illness, injury, aging, unemployment, and the need for long-term care. The system is primarily administered by the government and is funded through contributions shared by employees, employers, and the self-employed, alongside significant national treasury funding. Its importance lies in promoting social stability, reducing poverty among vulnerable groups, and ensuring that all citizens have access to essential healthcare and income security, thereby contributing to a cohesive and resilient society.

2. Applicable Objects & Scenarios

The Japanese social insurance system applies broadly but has specific categories:

  • Employees (Company Workers): All employees working for a company, regardless of nationality, are mandatorily enrolled by their employer in Health Insurance (Kenkō Hoken) and Employees' Pension Insurance (Kōsei Nenkin Hoken). This also includes Employment Insurance (Koyō Hoken) for unemployment benefits and Workers' Accident Compensation Insurance (Rōsai Hoken) for workplace injuries.
  • Self-Employed, Farmers, Freelancers, and Non-Employed Residents: Individuals who are not company employees are typically enrolled in the National Health Insurance (Kokumin Kenkō Hoken) and the National Pension (Kokumin Nenkin), administered by their local municipality (city/ward office).
  • Dependents: Spouses and children of insured persons may be covered as dependents under the primary insured's health insurance, subject to income criteria.
  • Specific Scenarios: Enrollment is required upon starting employment, moving to a Japanese municipality, or turning 20 years old (for National Pension). It is needed when seeking medical care, upon retirement, in case of unemployment, disability, or death of a breadwinner.

3. Core Conclusions

  • Mandatory Enrollment: Participation in the relevant health and pension insurance schemes is a legal obligation for all residents in Japan.
  • Employer-Managed for Employees: For company employees, the employer handles enrollment, premium calculations, and half of the premium payments for health and pension insurance.
  • Municipality-Managed for Others: Self-employed individuals and others not covered by employer-based insurance must proactively enroll at their local municipal office.
  • Lifelong Pension Requirement: To receive the full Old-Age Basic Pension, a minimum contribution period (currently a specific number of years) is required. Please verify with official sources for the exact number.
  • Portable Benefits: Insurance coverage and pension rights are retained when changing jobs or moving within Japan.
  • International Agreements: Japan has social security agreements with many countries to prevent double payment of premiums and to totalize pension contribution periods.

4. Procedures & Steps

For Company Employees:

  • Step 1: Preparation: The employee provides their personal information (including dependent information) and My Number (Social Security and Tax Number) to the employer.
  • Step 2: Application & Submission: The employer completes and submits the enrollment forms (e.g., "Health Insurance/Pension Insurance Enrollment Notification") to the nearest Japan Pension Service (Nenkin Jimusho) office or via online services. The employer withholds the employee's share of premiums from salary.
  • Step 3: Review & Confirmation: The Japan Pension Service processes the application. The employee receives a Health Insurance Card (Kenkō Hoken Shō) and a Pension Handbook (Nenkin Techō) or notification of their pension number.

For Self-Employed/Non-Employed Individuals:

  • Step 1: Preparation: Gather necessary documents: Residence Card, My Number Card, personal seal (inkan), and proof of address.
  • Step 2: Application & Submission: Visit the National Health Insurance and National Pension section at the local municipal office (City/Ward Office) within 14 days of becoming eligible (e.g., after moving to Japan, leaving a job). Submit the application forms for both National Health Insurance and National Pension.
  • Step 3: Review & Confirmation: The municipality issues a National Health Insurance Card and a National Pension Handbook. Payment slips for premiums (usually monthly or quarterly) will be sent by mail. Payment can be made at banks, convenience stores, or via automatic transfer.

5. Frequently Asked Questions (FAQ)

Q1: I just started a job at a company. Do I need to cancel my National Health Insurance myself? A: Yes. Once enrolled in your company's health insurance, you must promptly visit your municipal office to report the change and cancel your National Health Insurance. Failure to do so may result in being billed for both.

Q2: What happens to my pension if I work part-time? A: It depends on your hours, salary, and employment duration. Part-time workers may be enrolled in Employees' Pension if they meet certain criteria (e.g., working 20+ hours/week, expected employment >2 months, salary above a certain threshold). Please verify with official sources. If not eligible, you must join the National Pension.

Q3: I am planning to leave Japan permanently. Can I get a refund of my pension contributions? A: Yes, under the Lump-Sum Withdrawal Payment system. Foreign nationals who have paid into the pension for 6 months to under 10 years can apply for a partial refund after leaving Japan. Contributions for 10 years or more qualify for an old-age pension payable from age 65, even from abroad.

Q4: How are insurance premiums calculated? A: For Employees' Health/Pension Insurance, premiums are a percentage of your standard monthly remuneration (including bonuses), split 50/50 with your employer. The percentage rate varies by prefecture and insurance association. For National Health Insurance, premiums are calculated by the municipality based on the previous year's household income, number of insured, and assets. National Pension has a fixed monthly premium, with income-based exemptions available.

Q5: What is "Long-Term Care Insurance (Kaigo Hoken)" and who pays? A: This is a mandatory insurance for those aged 40 and over to cover nursing care services. Those aged 40-64 pay premiums as part of their existing health insurance premium. Those 65 and over pay premiums deducted directly from their public pension or via municipal bills.

Q6: Can I use my Japanese health insurance when traveling abroad? A: For medical treatment received overseas, you cannot use your insurance card directly. However, you can apply for reimbursement for part of the costs upon return by submitting claims to your insurer (your company or municipality), subject to limits and conditions.

6. Risks & Compliance

  • Legal Obligation: Non-payment of social insurance premiums can result in penalties, collection measures, and ultimately the loss of coverage and future pension benefits.
  • Accurate Reporting: It is the individual's responsibility to report life changes (marriage, birth, job loss, move) to the relevant office (employer or municipality) promptly.
  • No Double Coverage: You cannot be enrolled in both Employees' Health Insurance and National Health Insurance simultaneously. Proper procedures must be followed when switching.
  • Disclaimer: This article provides general guidance. Specific premium amounts, exemption criteria, and benefit calculations depend on individual circumstances and current laws. Always consult official sources or a qualified social insurance consultant for personal advice.

7. References & Sources

8. Related Topics

  • My Number System (Social Security and Tax Number)
  • Japanese Tax System: Income Tax and Resident Tax
  • Workers' Accident Compensation Insurance (Rōsai Hoken)
  • Unemployment Benefits (Employment Insurance)
  • Japanese Pension Types and Benefit Calculation
  • Long-Term Care Insurance (Kaigo Hoken) Services
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