Nenkin: the Bill That Waited Five Years
This is a new series on this blog: Life in Japan — the stories that happened between university and work, the ones that never fit the main chronology but taught the most expensive lessons. And there’s no better opener than my love letter from the Japanese pension system.
In early 2025, a few months before starting work, my company asked for one simple thing for the onboarding paperwork: my nenkin number.
One problem: I didn’t have one. Five years as a student in Japan, and I had never registered for nenkin at all.
The Rule Foreign Students Love to Skip
Nenkin (年金) is Japan’s national pension system, and the rule doesn’t care about your nationality: every resident of Japan aged 20 and above must be enrolled — students included, zero-income included.
Here’s what makes so many foreign students (me included) relax: nobody chases you at first. Don’t register, and nobody knocks on your door. It genuinely feels like it doesn’t exist.
But ignoring nenkin doesn’t erase it — it defers it. The bill sits quietly, waiting for the moment you enter the system: the day you first have an employer.
January 2025: Paying a Debt That Never Felt Like One
The moment the company asked for the number, I finally registered — around January–February 2025, just before starting work in April.
At registration, my student years were assessed one by one:
- Doctoral years one and two — exempted. Luckily, the student exemption (学生納付特例) was granted for those periods.
- Doctoral year three — refused. No exemption for that year, and the bill was due.
The result: in my first year of working, I paid nenkin double. The normal pension deduction from the monthly salary, plus the back-payments for the third doctoral year. Your first shakaijin salary feels like financial freedom — until you realize you’re funding pensions for two lives at once: present you, and past you who couldn’t be bothered with paperwork.
The Lesson: Register on Arrival, Not When Asked
If you are (or will be) a student in Japan, this is the only paragraph you need to remember:
Register for nenkin the first time you come to Japan — don’t wait until somebody needs the number. And if you’re a student, apply for the 学生納付特例 (student payment exemption) right after arriving, then renew it every single year. The application isn’t hard and can be done at the city office. With a clean exemption on file each year, no arrears are waiting for you on your first day of work — and the exempted periods still count in your pension record.
Don’t be me: hoping the problem disappears if you don’t look at it. The system is patient. Far more patient than your wallet.
Check the Current Rules
Student-exemption rules, back-payment windows, and nenkin rates change over time. Before making decisions based on this article, check the official Japan Pension Service (日本年金機構) pages. My experience is from the 2025 cycle.