What happens to social insurance when you hire someone for short hours

In short: At a company with fewer than 51 employees, whether someone joins social insurance is decided by the three-quarters test alone. If both the prescribed working hours per week and the prescribed working days per month are less than three-quarters of those of an ordinary worker, they do not join. Employment insurance is separate: 20 hours a week or more is the dividing line.

When hiring a part-timer, we are often asked "up to how many hours can I go without having to enrol them in insurance?" The answer changes with the size of the company — and it will keep changing over the next ten years. The standard you set today is the kind of standard that will no longer work as it is a few years from now.

From how many hours does someone join social insurance?

Health insurance and employees' pension insurance contain provisions that exclude short-time workers from insured status (Health Insurance Act, Article 3, paragraph 1, item 9; Employees' Pension Insurance Act, Article 12, item 5). This is where the three-quarters test comes in.

At a company where ordinary workers work 40 hours a week and 20 days a month, the boundary is 30 hours a week and 15 days a month. If both are less than three-quarters, the person does not become an insured person. If even one of them is three-quarters or more, they are an insured person.

The three-quarters test decides the matter on its own only at a company that is not a specified covered workplace — that is, a company where the number of insured persons under employees' pension insurance is 50 or fewer on a regular basis. The basis is Act No. 62 of 2012 (Heisei 24), Supplementary Provisions, Article 17, paragraph 1 (employees' pension insurance) and Supplementary Provisions, Article 46, paragraph 1 (health insurance), which provide that "for the time being, a specified short-time worker working less than three-quarters who is employed at a covered workplace other than a specified covered workplace shall not be treated as an insured person."

At a company where the number of insured persons regularly exceeds 50, a person becomes an insured person even below three-quarters if all of the following apply.

	Requirement
①	Prescribed working hours of 20 hours or more per week
②	Prescribed wages of 88,000 yen or more per month
③	Not a student

As set out below, ② is scheduled to be abolished.

Does employment insurance use the same standard as social insurance?

No. For employment insurance it is 20 hours a week. The Employment Insurance Act excludes from coverage "a person whose prescribed working hours per week are less than 20 hours" (Article 6, item 1 of that Act).

Workers' accident compensation insurance is different again: it has no working-hours requirement. Employ even one worker and the business is covered, and someone working one hour a week is covered too. Setting the three side by side:

Prescribed working hours per week	Workers' accident compensation insurance	Employment insurance	Health insurance / employees' pension insurance (company with fewer than 51 employees)
Less than 20 hours	Covered	Not covered	Not covered
20 hours or more but less than 30 hours	Covered	Covered	Not covered
30 hours or more	Covered	Covered	Covered (at a company on 40 hours a week)

The band from 20 to 30 hours is the one most often misunderstood. It is the state in which the person is in employment insurance but not in social insurance. What happens is that someone the employer assumed "cannot be insured" asks for a separation certificate, and only then does the employer notice.

Note that "30 hours or more" in the social insurance column assumes a company where ordinary workers work 40 hours a week. At a company where ordinary workers have shorter prescribed hours, the boundary comes down too. At a company on 35 hours a week it is 26.25 hours. Work it out from the prescribed working hours in your own rules of employment.

Where has the "1.06 million yen wall" gone?

It is moving towards disappearing. The wage requirement in ② above (88,000 yen or more per month, which comes to roughly 1.06 million yen a year) was what the so-called "1.06 million yen wall" actually was.

The Ministry of Health, Labour and Welfare states that this wage requirement is scheduled to be abolished in October of Reiwa 8 (2026). The reason is that the regional minimum wages for FY Reiwa 7 (FY2025) came to exceed 1,016 yen an hour in every prefecture. At 1,016 yen an hour, 20 hours a week reaches 88,000 yen a month, so once the working-hours requirement in ① is met, ② is met automatically. The reasoning is that it has therefore ceased to function as a requirement.

It is, however, "scheduled." Act No. 74 of 2025 (Reiwa 7) sets the timing of the abolition as "a day to be specified by cabinet order within 3 years from promulgation," and the cabinet order fixing that date could not be confirmed as at the time of writing (13 August 2026). Both the Ministry of Health, Labour and Welfare and the Japan Pension Service use the wording "scheduled to be abolished." If you are building a staffing plan on the assumption of that date, check again immediately beforehand.

Once it is abolished, whether someone joins comes down to just 2 questions: "20 hours a week or more?" and "not a student?" Because the line drawn by wages disappears, raising the hourly rate will not change whether the person joins. It means that adjusting hours "so as not to go over 1.06 million yen" ceases to have any point.

Note that the so-called "1.3 million yen wall" (the standard for being a dependant) is not abolished by this reform. The 1.06 million yen question and the 1.3 million yen question belong to different schemes, so take care not to mix them up.

How long will this standard last?

The company-size requirement itself disappears in stages over ten years.

Timing	Size at which a company becomes a specified covered workplace
Current	51 or more insured persons under employees' pension insurance
October 2027	36 or more
October 2029	21 or more
October 2032	11 or more
October 2035	10 or fewer also covered (abolition of the size requirement completed)

(Act No. 74 of 2025 (Reiwa 7). Ministry of Health, Labour and Welfare, "Key points on the expansion of social insurance coverage for short-time workers," prepared January of Reiwa 8 (2026))

In the end, the line drawn by company size disappears. The state of "we have 50 or fewer, so it does not concern us" will not continue. A company with 20 employees is covered from October 2032, and even a company with 10 employees from October 2035.

The changes scheduled alongside this are also worth listing.

• Support in adjusting insurance premiums for those newly brought into coverage (for 3 years) — October 2026
• Raising of the upper limit of the standard monthly remuneration — to 680,000 yen in September 2027, 710,000 yen in September 2028 and 750,000 yen in September 2029
• Expansion of coverage for sole proprietorships (all industries, five or more workers on a regular basis) — October 2029 (workplaces already in existence at that time are outside the scope for the time being)

Do you increase the number of people employed for short hours, or narrow the headcount and give each person longer hours? Both designs converge on the same conclusion within a few years. Building the staffing plan on that assumption saves you the work of rebuilding it later.

Where you employ a family member for short hours, the treatment under employment insurance becomes a separate problem. See Three things that trip you up when you put a family member on the payroll. If you plan to convert part-timers into regular employees, reading If you are going after a subsidy, it is decided by the form of the first contract first will change how you settle the contract at the entrance.

Frequently asked questions

Q. The prescribed working hours are 28 a week, but in the busy season she actually works 32. Which is used to judge?
A. The basis for the judgement is the prescribed working hours. However, where actual working hours consistently exceed the prescribed hours, this may be assessed as a state of affairs in which the prescribed working hours ought to be revised to match reality. The treatment differs depending on whether the excess was "temporary" or whether "that has in substance become the prescribed hours," so if overtime in the busy season arises at the same time of year and to the same extent every year, please consult us.

Q. In counting the 51 employees, are part-timers included?
A. What is used in determining a specified covered workplace is the number of insured persons under employees' pension insurance. A part-timer who is an insured person counts, while a short-hours worker who is not an insured person does not. Multiple covered workplaces under the same proprietor are also counted together. The expression used is "number of employees," but note that it is not a head count of the people on the books.

Q. When the wage requirement is abolished, will all our current part-timers be enrolled?
A. At a company with 51 or more employees, those working 20 hours or more a week who are not students become subject to enrolment. However, a person who is covered by the reduction exception under the Minimum Wage Act and whose monthly wage is less than 88,000 yen is as a rule still outside the scope after the abolition (voluntary enrolment on application is possible). At a company with 50 or fewer employees, the abolition of the wage requirement alone changes nothing; such companies are affected when the company-size requirement comes down.

Q. Can I lower the hourly rate to offset the increase in insurance premiums?
A. Lowering wages amounts to a disadvantageous change to working conditions, so it cannot be done unilaterally without the person's consent. Even where it is done by amending the rules of employment, the reasonableness of the amendment will be examined. A reduction on the grounds of the expansion of coverage falls into the category where reasonableness is difficult to explain. This judgement depends on the individual circumstances, so please consult us in advance if you are considering it. For fees, see the fee schedule.

Sources for this article

• Health Insurance Act (健康保険法, Act No. 70 of 1922), Article 3, paragraph 1, item 9
• Employees' Pension Insurance Act (厚生年金保険法, Act No. 115 of 1954), Article 9 and Article 12, item 5
• Act Partially Amending the National Pension Act and Other Acts to Strengthen the Financial Base and Minimum Guarantee Function of the Public Pension System (公的年金制度の財政基盤及び最低保障機能の強化等のための国民年金法等の一部を改正する法律, Act No. 62 of 2012 (Heisei 24)), Supplementary Provisions, Article 1, item 5 (in force 1 October 2016 (Heisei 28)); Supplementary Provisions, Article 17, paragraph 1 (employees' pension insurance); Supplementary Provisions, Article 46, paragraph 1 (health insurance)
• Employment Insurance Act (雇用保険法, Act No. 116 of 1974), Article 4, paragraph 1 and Article 6, item 1. Article 6 is a provision that has no paragraphs, so the citation is "Article 6, item 1"
• Act Partially Amending the National Pension Act and Other Acts to Strengthen the Functions of the Pension System in Light of Socio-Economic Change (社会経済の変化を踏まえた年金制度の機能強化のための国民年金法等の一部を改正する等の法律, Act No. 74 of 2025 (Reiwa 7); enacted 13 June 2025, promulgated 20 June)
• Ministry of Health, Labour and Welfare, "Key points on the expansion of social insurance (health insurance and employees' pension insurance) coverage for short-time workers" (prepared January of Reiwa 8 (2026)) — the timetable for the company-size requirement, the scheduled abolition of the wage requirement, and the statement on the 1,016 yen minimum wage
• Japan Pension Service, "Expansion of the application of health insurance and employees' pension insurance to short-time workers" (updated 17 April 2026)
• The cabinet order fixing the date of abolition of the wage requirement could not be confirmed as at 13 August 2026 (unverified). Both the Ministry of Health, Labour and Welfare and the Japan Pension Service use the wording "scheduled to be abolished in October of Reiwa 8"
• All provisions are those in force as confirmed through e-Gov law search as of 13 August 2026

This article stops short of deciding who you should consult. Designing prescribed working hours, determining whether enrolment is required, filing notifications of acquisition of insured status, and reviewing the rules of employment are the work of a Shakai Hoken Roumushi (Certified Social Insurance and Labor Consultant). For income tax matters such as the spouse deduction, we will point you to a tax accountant, whom you engage directly under a separate contract. We do not receive referral fees. Fees for consulting 四葉社会保険労務士事務所 are set out in the fee schedule, and the questions we are asked most often are collected in frequently asked questions.

This article is general information. A judgement on your particular circumstances is made by a qualified professional after a meeting. Written by Joji Uramatsu (Shakai Hoken Roumushi (Certified Social Insurance and Labor Consultant), Gyoseishoshi (Certified Administrative Procedures Legal Specialist), Registered Real Estate Transaction Specialist).