Why Your Take-Home Drops at 40 in Japan

Last updated: 13 October 2026 · 協会けんぽ rates for the 2026 fiscal year · figures for the 2026 tax year

Around your 40th birthday a new line appears on your payslip: long-term care insurance (介護保険料, kaigo hokenryō), sometimes translated as nursing-care insurance. If your employer’s health insurance is 協会けんぽ (Kyōkai Kenpo, the Japan Health Insurance Association), the premium is 1.62% of your insurance grade, and your employer pays half of it, so 0.81% comes out of your pay. On a ¥300,000 grade that is ¥2,430 a month. It starts with the premium for the month that contains the day before your 40th birthday, which usually reaches the payslip a month later, and it is charged for as long as you are 40 to 64. The payslip falls by a little less than the premium, because the premium is deducted before income tax. To see it on your own salary, set Age to “40 to 64” in the take-home calculator.

This is a general explanation for somebody paid a salary by one employer in Japan. Your employer and your health insurer are the authority on your own payslip.

What the premium is

Japan’s long-term care insurance pays for the care of older people who need it. Under the Long-Term Care Insurance Act (介護保険法), everybody aged 40 to 64 with an address in Japan who is in a Japanese health insurance plan is a category 2 insured person (第2号被保険者), and pays a premium for it through that plan. There is no form to file: your health insurer adds it to your health insurance premium, and your employer takes it from your pay with the rest of social insurance. Some payslips show it as its own line, 介護保険料; others fold it into the health insurance line.

The premium is your insurance grade (標準報酬月額, the standard monthly remuneration the health insurance premium is also charged on) times the care insurance rate. Your employer pays half of the premium and you pay the other half, as with health insurance itself. Bonuses are charged too: 0.81% of the standard bonus amount (標準賞与額), on top of health insurance.

Each insurer sets its rate every year from what it has to pay into the care system. 協会けんぽ uses one rate for every prefecture, unlike its health insurance rate: it was 1.59% for the 2025 fiscal year and is 1.62% from the premium for March 2026, the first one deducted from April pay.

The month it starts

The rule turns on the day before your birthday: for this purpose you reach an age on the day before the birthday itself. You become a category 2 insured person on the day before your 40th birthday, and the premium is charged for the whole of the month that day falls in, however late in the month it is. Your employer then takes each month’s premium from the following month’s pay, which is how most payrolls run. 協会けんぽ gives two examples:

• Born on 2 May: the day before is 1 May, so the May premium is the first, and it comes out of June’s pay. Anybody born from 2 May to 31 May is in the same position.
• Born on 1 May: the day before is 30 April, so the April premium is the first, and it comes out of May’s pay — a month earlier than everybody else born in May.

The month is charged in full: turning 40 on the 31st costs the same as turning 40 on the 2nd. Nothing is spread out or charged by the day.

What it takes from three salaries

The table puts the same salary at 39 and at 40, worked out with the same engine as the take-home calculator. The assumptions: twelve equal monthly salaries and no bonus, single with no dependents, working in Tokyo and insured through 協会けんぽ at its 2026 rates, with the 2026 withholding tables. The take-home columns are a whole year, with the resident tax for that year worked out on a previous year at the same age.

The premium is 0.81% of the grade: on ¥5,000,000, a monthly salary of ¥416,667 sits in the ¥410,000 grade, and 0.81% of that is ¥3,321. The payslip falls by less, ¥3,081, because social insurance comes off before income tax is withheld, so the tax taken each month goes down by ¥240.

Over a year on ¥5,000,000, the premiums add up to ¥39,852. Income tax for the year is ¥2,000 lower, settled in the year-end adjustment (年末調整), and resident tax is ¥3,900 lower, which leaves ¥33,952 a year. The higher the salary, the more of the premium the tax system gives back: on ¥7,000,000 the income left after deductions is in the 20% income tax band, so income tax falls by ¥11,800 and resident tax by ¥5,900 against ¥57,348 of premiums.

The year you turn 40

In that first year the change comes in pieces. The payslip falls from the first month the premium is taken, by the amount in the “payslip lower” column. Fewer months are charged than in a whole year, and the income tax part is settled in December with the rest of the year-end adjustment. The resident tax part is the last to arrive: resident tax is charged on the previous year’s income, so premiums paid this year lower the bill that starts in June next year. Somebody who turns 40 in May 2026 sees the payslip change in June 2026 and the resident tax change in June 2027.

If your employer has its own health insurance society

Larger companies often insure their staff through a health insurance society (健康保険組合, kenkō hoken kumiai) instead of 協会けんぽ. The age rule is the same, but the society sets its own care insurance rate each year, and its rules can have the employer pay more than half. A society’s rules can also charge the care premium to an employee outside the 40 to 64 range — under 40, or 65 and over — who has a dependent in it, such as a spouse: a specified insured person (特定被保険者). If that describes you, the premium can start before 40 or carry on after 65. The figures on this page and in the calculator use 協会けんぽ’s rate, so for a society check its website or your payslip for the rate, and treat the table as a guide to the size of the change rather than the exact amount.

At 65

The same day-before rule ends it. From the month that contains the day before your 65th birthday you are no longer a category 2 insured person, and no premium is charged for that month. Because the premium is taken a month behind, the payslip changes a month later: born on 2 May, the April premium is the last, taken from May’s pay, and June’s payslip has none; born on 1 May, the last is March’s, taken from April’s pay. Health insurance carries on. You become a category 1 insured person (第1号被保険者) instead, and the municipality where you live charges the premium directly. The ¥5 million salary guide follows that step on one salary.

Questions people ask

When does long-term care insurance start coming out of my pay?

With the premium for the month that contains the day before your 40th birthday. Employers usually take each month’s premium from the next month’s pay, so it first shows on the payslip a month later. If your birthday is on the 1st of a month, the day before is in the previous month, and everything starts a month earlier.

How much less will I take home after turning 40?

On a ¥5,000,000 salary in Tokyo, ¥3,081 a month on the payslip: the premium is ¥3,321, and income tax withheld falls by ¥240 because the premium is deducted before tax. Over a whole year, once resident tax has caught up, it is ¥33,952.

I do not plan to stay in Japan when I am old. Do I still pay it?

Yes. Membership follows your age, an address in Japan and Japanese health insurance, not your nationality or your plans, so everybody aged 40 to 64 in an employer’s health insurance pays it. The Lump-sum Withdrawal Payment for people who leave Japan is a pension benefit, and care insurance premiums are not part of it.

Does the premium stop at 65?

No premium is charged for the month that contains the day before your 65th birthday. With each month’s premium taken from the next month’s pay, the last one comes out of that month’s pay and the payslip after it has none. You still pay care insurance after that, but to the municipality where you live, which charges it directly. Health insurance itself carries on through your employer — and a health insurance society can keep charging an employee of 65 or over who has a dependent aged 40 to 64.

For the other month of the year when the insurance lines move on their own, see why your take-home drops in October.

Sources

• 協会けんぽ (Japan Health Insurance Association) — 協会けんぽの介護保険料率について (1.62% from the March 2026 premium, 1.59% before it, one rate for the whole country, added to the health insurance rate for category 2 insured persons). Japanese, opened 13 October 2026.
• 協会けんぽ Ibaraki branch — 介護保険制度と介護保険料について (the day before the 40th and 65th birthdays, the examples for 2 May and 1 May at both ages, the premium taken in the following month’s bill for employees). Japanese.
• Long-Term Care Insurance Act (介護保険法) Articles 9 and 10 (category 2 insured persons are aged 40 to 64, live in Japan and are in a health insurance plan; membership begins on reaching 40). Read on e-Gov.
• Health Insurance Act (健康保険法) Article 156 (the care premium is charged on the insurance grade and on bonuses), Article 160, paragraph 16 (each insurer sets its care insurance rate every year), Article 161 (employer and employee pay half each), Article 162 (a health insurance society may raise the employer’s share), Article 167 (the employer takes the previous month’s premium from pay) and Supplementary Provisions Article 7 (a society may charge specified insured persons). Read on e-Gov.