This is one of those Japanese payslip changes that arrives with no warning and no English explanation. Mio doesn't guess — here's what actually happened and why.
Long-term care insurance (kaigo hoken, 介護保険) is a nationwide public insurance system, run through municipalities, that helps pay for care for older people — home help, day services, care facilities, and similar support. It's a separate program from your regular health insurance, but for working-age people the premium is bundled into the same deduction, which is why it can look like your health insurance simply "went up."
Enrollment in long-term care insurance is mandatory from age 40. Under the system, you become an insured person from the month that includes your 40th birthday, and the premium starts being collected from that point. So on the payslip for that month, a new charge appears — nothing about your job, pay, or health insurance changed; you simply crossed the age threshold where this premium begins. That's the mechanism behind "my salary is the same but my deduction went up at 40."
The system splits insured people into two categories, and the collection method differs:
| Category | Ages | How the premium is collected |
|---|---|---|
| Category-2 insured (第2号被保険者) | 40–64 | Collected together with your health insurance, typically deducted from pay along with your health-insurance premium. |
| Category-1 insured (第1号被保険者) | 65+ | Billed separately by your municipality — commonly deducted from your pension, or paid directly. |
So the deduction you notice at 40 is the Category-2 mechanism. When you reach 65, the way you pay changes rather than the fact that you pay.
If you're a foreign resident enrolled in Japan's public health insurance (whether employees' health insurance or National Health Insurance), the long-term care insurance premium applies to you the same way it applies to Japanese residents once you're in the 40–64 age range. Nationality does not create an exemption. Your obligation follows your enrollment in the insurance system, not your passport.
If you're unsure which health insurance you're enrolled in, that determines how the premium reaches you — see health insurance in Japan for foreigners.
The premiums fund Japan's long-term care services for older people: in-home care and visiting help, day-care and rehabilitation services, short stays, and care facilities, among others. It's a shared-cost system — everyone 40 and over contributes so that care is available when it's needed, typically later in life or, in limited cases, earlier for specific age-related conditions. In other words, it's not a fee for something you use today; it's participation in the pool that pays for care across society.
The deduction at 40 is real, mandatory, and correct — not an error. If your take-home dropped right after your 40th birthday with no other change, long-term care insurance is almost certainly the reason. Foreigners pay it like everyone else. It's worth confirming the exact amount on your payslip so you know what's yours going forward. See the full life-admin roadmap for Japan →
Mio