How Japan’s Employees’ Pension Insurance (Kōsei Nenkin) Works

Japan’s Employees’ Pension Insurance, known locally as Kōsei Nenkin, is the earnings-based layer of the country’s public pension system, sitting on top of the flat-rate National Pension that covers every resident. If you work as a salaried employee in Japan, you’re almost certainly enrolled. Contributions run at 18.3% of your standardized monthly pay, split evenly between you and your employer, and the system pays out old-age, disability, and survivors’ benefits tied to how long you contributed and how much you earned.¹

Who Has to Enroll

Every incorporated company in Japan participates, no matter how few people it employs. Unincorporated businesses also fall under the mandatory rules if they have five or more workers in a covered industry such as manufacturing.² Full-time employees, officers, and representatives at those workplaces are enrolled automatically.

Part-timers get pulled in on two separate tests. The general rule: if your weekly hours and monthly workdays are at least three-quarters of what full-time staff at the same employer work, you’re covered.² Since October 2024, a broader test applies at companies with 51 or more employees: part-timers working at least 20 hours a week and earning ¥88,000 or more per month in base wages must also be enrolled. Overtime, bonuses, and commuting allowances don’t count toward that ¥88,000, and students are excluded.³

Compulsory participation runs up to age 70. After that, enrollment ends.¹ Employers who skip enrolling qualifying staff can face administrative penalties and orders to pay back premiums for the missed period.

What You and Your Employer Pay

Your actual salary is translated into a bracket called the Standard Monthly Remuneration, or SMR. The brackets run from ¥88,000 at the low end to ¥650,000 at the top. The system takes 18.3% of whichever bracket you fall into, and the bill is split evenly: 9.15% comes out of your paycheck, 9.15% comes from your employer.⁴ Your National Pension contribution is baked into that same payment, so you don’t pay into the basic tier separately.

Bonuses are hit with the same 18.3% rate, but only up to ¥1.5 million per payment. Anything above that isn’t subject to pension premiums.⁴ Your employer runs the calculations, deducts your share from payroll, adds its own share, and sends everything to the Japan Pension Service. Premiums are due by the last day of the month following each pay period, with delinquency charges for late remittance.

Because the SMR is capped at ¥650,000, very high earners contribute the same amount as someone earning at that ceiling, and their eventual benefit reflects that cap too.

Retirement Benefits

You can start drawing an old-age Employees’ Pension at 65, provided you have at least 10 years of total pension coverage (Employees’ Pension months and National Pension months combined).⁵ The Employees’ Pension pays out on top of the flat-rate Old-age Basic Pension, so a career of salaried work produces a noticeably larger retirement income than National Pension coverage alone. Even a single month of Kōsei Nenkin coverage adds an earnings-related component to your retirement benefit.⁶

How Your Benefit Is Calculated

The earnings-related benefit uses two multipliers depending on when your coverage occurred. For months from April 2003 onward, the formula is your average Standard Remuneration (including bonuses) multiplied by 5.481/1000, multiplied by the number of covered months in that period. For coverage before April 2003, a slightly higher multiplier of 7.125/1000 applies to your average Standard Monthly Remuneration.⁶

For a typical worker with about 35 years of contributions at a middling salary, the Employees’ Pension portion alone tends to add somewhere between ¥90,000 and ¥110,000 per month on top of the Basic Pension. Higher earners with longer careers get more, but the ¥650,000 SMR ceiling limits how much the system will credit no matter how large your paycheck runs.

Claiming Early or Deferring

You can start payments as early as 60, at a permanent cost. For anyone born on or after April 2, 1962, the pension is trimmed by 0.4% for every month you claim before 65. Start at exactly 60 and you lock in a 24% reduction for life.⁷

Deferring works the opposite way. Each month you wait past 65 raises your benefit by 0.7%, or 8.4% a year. Since 2022, you can defer as far as age 75, which increases the eventual payment by up to 84%. It pays off only if you live long enough to make up for the years without any pension income.

If You Keep Working

If you continue working past 65 and your combined monthly wage and pension exceeds a threshold, part of your pension is temporarily suspended. That threshold rises from ¥500,000 to ¥620,000 per month in April 2026, meaning fewer working retirees will see their benefits cut.³

Disability and Survivors’ Coverage

Employees’ Pension coverage isn’t only about retirement. A worker who develops a serious disability from an illness or injury first examined during a covered period can receive a Disability Employees’ Pension. The system uses three grades, with Grade 1 the most severe. Grade 1 recipients receive 125% of the Grade 2 amount, and Grade 3 is a lower fixed benefit. Grade 1 and Grade 2 recipients also collect the flat-rate Disability Basic Pension; Grade 3 is covered only through the Employees’ Pension.

If an enrolled worker dies, the Survivors’ Employees’ Pension supports dependent family members. Eligible survivors typically include the spouse and children first, then parents, grandchildren, or grandparents. The benefit equals three-quarters of the pension the deceased had earned or would have been entitled to. These payments are taxable in Japan as miscellaneous income, though pension income deductions can soften the bill.⁸

Coverage for a Dependent Spouse

If you’re enrolled in Employees’ Pension Insurance, your spouse can be covered under the National Pension without paying premiums. These dependents are called Category 3 insured persons. To qualify, the spouse must be 20 to 59 years old, live in Japan, earn under ¥1.3 million a year, and earn less than half of what you do, though the Japan Pension Service will sometimes make exceptions when you’re clearly the household’s primary earner.⁹

Registration isn’t automatic. Your employer has to submit a Category III Insured Person enrollment form to the Japan Pension Service within 14 days.⁹ It’s easy to miss during onboarding. A dependent spouse who never gets registered loses those credited pension years, and the missing years reduce their own future Basic Pension.

The Enrollment Paperwork

To enroll a new hire, an employer needs the worker’s Basic Pension Number, which appears on the Basic Pension Number Notice issued the first time someone joins the pension system.¹⁰ Older workers may still hold a blue or orange pension handbook that serves the same purpose. If neither is available, the employee’s My Number identification code can be used instead. The employer also collects the legal name, date of birth, home address, expected monthly salary, and exact start date.

The core form is the Health Insurance and Employees’ Pension Insurance Insured Person Qualification Acquisition Report, filed within five days of the hire date at the Japan Pension Service branch covering the business location.² Filings go through e-Gov or the G-Biz ID system, by mail, or in person. After processing, the Japan Pension Service issues a confirmation notice with the insured status and the calculated premium bracket, and the first payroll deduction usually appears the following month. An incorrect starting salary figure forces retroactive SMR adjustments later, so getting it right matters.

If You Leave Japan: The Lump-Sum Withdrawal

Foreign nationals who leave Japan after a short period of work can claim a partial refund of their Employees’ Pension contributions. You qualify if you aren’t a Japanese citizen, you’re no longer covered by the system, and you file within two years of leaving.¹¹ The clock starts the day you leave.

The formula is your average Standard Monthly Remuneration multiplied by a payout rate keyed to your months of coverage, using half the insurance premium rate and capping at 60 months of coverage.¹² For the period from September 2025 to August 2026, payout rates range from 0.50 at six months of coverage up to 5.00 at 60 months or more. A worker with an average SMR of ¥300,000 and five years of coverage would receive roughly ¥1.5 million before tax.

Japan withholds 20.42% income tax on the lump sum. You can recover that withholding by appointing a tax representative in Japan before you leave. After you receive the official payment notice, the representative files a quasi-final tax return at the local tax office; the refund is deposited into their Japanese account and then remitted to you abroad. Some people hire an administrative scrivener to manage this. Skip the step, and the withholding is permanent.

Weigh the trade-off carefully. Taking the lump sum erases those contribution months from your Japanese record. If your home country has a totalization agreement with Japan, the erased months can no longer count toward pension eligibility in either country. That’s a real cost if you might return to Japan or if you need those credited years under a social security agreement.

Cross-Border Points for US Workers

The US-Japan totalization agreement prevents workers from paying into both countries’ pension systems at once and lets you combine coverage from both. If you don’t have enough US credits to qualify for Social Security on American work alone, your Japanese coverage can help you cross the eligibility line, as long as you have at least six US credits (about a year and a half of work). The reverse works too: American coverage can help you qualify for a Japanese pension. Benefits combined this way are prorated based on actual coverage in each country.¹³

To avoid dual contributions during a temporary assignment, your employer requests a certificate of coverage (form J/USA 6) from the Japanese social insurance agency where your taxes are collected. The certificate proves you’re covered under one country’s system and exempts you from the other.¹³ A worker sent from the US to Japan usually stays in US Social Security for up to five years. Workers hired locally in Japan generally pay into the Japanese system. Get the certificate before the assignment starts; recovering double-paid contributions after the fact is a headache.

When you eventually collect a Japanese pension while living in the US, the US-Japan income tax treaty gives the taxing right to your country of residence. Pensions, including Japanese social security payments, are taxable only in the United States for a US resident, so Japan shouldn’t withhold tax on payments sent to you in the US, and you report the income on your US return.¹⁴

Whether a Kōsei Nenkin account belongs on FinCEN Form 114 (the FBAR) is less settled. US persons must file when the aggregate value of foreign financial accounts tops $10,000 at any point in the year. The IRS carves out certain retirement accounts described in Internal Revenue Code Sections 408 and 401(a), but those describe US-specific plans like IRAs and 401(k)s, not a Japanese government-run pension.¹⁵ Practitioners disagree on whether Kōsei Nenkin is even a “foreign financial account” in the FBAR sense, since you can’t withdraw the balance at will. Given the size of FBAR penalties, checking with a cross-border tax advisor before deciding not to report is the safer path.

Inside Japan, pension payments are treated as miscellaneous income and qualify for a pension income deduction that varies by age and total income.⁸ For recipients 65 and over who are eligible for the Old-age Basic Pension, no withholding applies if total pension income stays below ¥800,000 a year.

1
Japanese Law Translation. Employees’ Pension Insurance Act
2
Japan Pension Service. Enrollment in Employees’ Pension Insurance and Employees’ Health Insurance
3
Ministry of Health, Labour and Welfare. Overview of Pension System Revision
4
Japan Pension Service. Employees’ Pension Insurance Contributions
5
Japan Pension Service. Old-Age Basic Pension
6
Japan Pension Service. Old-Age Employees’ Pension
7
Promotion and Mutual Aid Corporation for Private Schools of Japan. Early Payment of Old-Age Employees’ Pension
8
Promotion and Mutual Aid Corporation for Private Schools of Japan. Taxation Pension Benefits
9
Japan Pension Service. Report of Dependents
10
Japan Pension Service. Japanese National Pension System
11
Japan Pension Service. Lump-Sum Withdrawal Payments
12
Promotion and Mutual Aid Corporation for Private Schools of Japan. Lump-Sum Withdrawal Payment Pamphlet
13
Social Security Administration. Totalization Agreement with Japan
14
U.S. Department of the Treasury. United States – Japan Income Tax Convention
15
Internal Revenue Service. Details on Reporting Foreign Bank and Financial Accounts