Labor at a dental clinic and dental lab — part-time and shorter-hours dental hygienists and how to think about social insurance

In short: For social insurance, a dental clinic is a "medical business" and a dental lab a "manufacturing business," the opposite of service industries such as restaurants and beauty salons. Even a sole proprietorship becomes compulsorily covered for health and pension once it regularly uses five or more staff, and a corporation is covered with even one director. Part-time dental hygienists and dental assistants, and technicians' overtime, are designed on this foundation, drawing the line by hours.

A dental clinic typically centers on a director who is a dentist, with dental hygienists, dental assistants, and reception, and dental technical work outsourced to an external dental lab. It is easy to assume "we're small, so social insurance is irrelevant" or "technicians are craftsmen, so time management isn't needed," but missing the industry classification and the way hours are counted leads to later back premiums and unpaid overtime. First, pin down the foundation.

When you hire dental hygienists and assistants part-time, what happens to social insurance?

First, confirm whether the dental clinic is a workplace covered by social insurance (health insurance and employees' pension). This is where it is the opposite of a sole-proprietor service business such as a beauty salon — an important point.

Business form	Health insurance / employees' pension
Corporation (medical corporation, KK, etc.)	Compulsory even with the director alone
Sole-proprietor dental clinic	Compulsory with five or more regular staff (the medical business is among the statutory applicable industries)

Article 3(3) of the Health Insurance Act and Article 6 of the Employees' Pension Insurance Act make individual workplaces with five or more regular staff compulsorily applicable, while excluding service businesses such as agriculture/forestry/fisheries, restaurants, and barber/beauty businesses from the applicable industries. "The treatment of disease and other medical business" is among the applicable industries, so a sole-proprietor dental clinic is a compulsorily applicable workplace once it regularly has five or more staff. This is the reverse of a barber/beauty business, which as a sole proprietorship is not compulsory even with five or more staff; the difference becomes clear when read alongside opening a hair salon — how do you set commission pay, chair rental, and social insurance.

Once it is a covered workplace, whether each dental hygienist or assistant enrolls part-time is judged by comparison with a regular worker.

Test	Enrollment basis
Three-quarters test	Prescribed weekly hours and monthly working days are both three-quarters or more of a regular worker's
Coverage expansion (specified applicable workplace)	At a workplace with a certain number of insured persons, enrollment applies if 20 or more weekly hours, monthly wage of 88,000 yen or more, expected employment over two months, and not a student

The counting is summarized in what happens to social insurance when you hire for short hours.

When setting shorter-hours or "within-the-dependent-limit" shifts, what should you watch?

Dental hygienists are a profession where many work shorter hours while balancing childcare and family. To meet a wish to work "within the dependent limit," think separately about the entrance to social insurance and to employment insurance.

• Social insurance: a shift below the three-quarters test does not enroll as a rule, but if the workplace is a specified applicable workplace, it becomes subject to enrollment under conditions such as 20 or more weekly hours. The firm-size requirement is expanding in stages: 51 or more insured persons (36 or more from October 2027). Further, the wage requirement of 88,000 yen or more per month is set to be abolished in October 2026.
• Employment insurance: a worker with 20 or more prescribed weekly hours (10 or more from October 2028) and expected employment of 31 days or more is insured.

The firm-size expansion schedule is in social insurance coverage expands to 36 or more from October 2027, and explanations for those working within the dependent limit are in what employers should do when the 1.06-million-yen income wall is abolished. Even a clinic of a few people should design shifts on the premise that "even if no one is covered now, some will be brought in by next year's revision" if the number of insured persons reaches the threshold, so as not to scramble later. Write the prescribed hours and working days of shorter-hours staff clearly in the employment contract and work rules.

How do you manage a dental lab technician's working hours and overtime?

For social insurance, a dental lab is a "manufacturing/processing business," which is an applicable industry, so even a sole proprietorship becomes compulsorily covered for health and pension with five or more regular staff (a corporation with even one). Here too, like a medical institution, it is the reverse of a service business.

Working-hour management follows the Labor Standards Act's principles regardless of industry.

Item	Content
Statutory working hours	In principle 8 hours a day, 40 hours a week (Article 32, Labor Standards Act)
Overtime / holiday work	Cannot be ordered without concluding and filing a Article 36 agreement (Article 36)
Premium wages	Premium wages for overtime, late-night, and holiday work (Article 37)

Dental technical work is a field prone to long hours under deadline pressure. Overtime pay is not waived just because the work "feels like commission or subcontracting," and Article 36 agreements and premium wages apply as they are to an employed technician. Making the prescribed hours, breaks, and overtime treatment clear in work rules and attendance records, and objectively grasping actual hours, prevents unpaid-overtime trouble. Note that even where work is given to a technician on a "subcontract" basis, if there is command/supervision or restraint of time and place, the reality may be judged to be employment; the line is decided by the reality, not by the title of the contract.

At a clinic with the director plus a few staff, are work rules required?

The obligation to prepare and file work rules arises from a workplace regularly using ten or more workers (Article 89, Labor Standards Act). A dental clinic with fewer than ten workers besides the director need not prepare or file them. However, some things are required regardless of headcount.

Matter	Headcount requirement
Preparation/filing of work rules	Compulsory with ten or more regularly (Article 89)
Notice of working conditions	Required from the first worker (Article 15)
Harassment-prevention measures	Compulsory regardless of headcount
Measures under the Childcare and Family Care Leave Act	Compulsory regardless of headcount

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Even where not compulsory, the more a dental clinic mixes shorter-hours, part-time, and technician working styles, the greater the value of putting rules on prescribed hours, shifts, leave, and conduct into writing. The headcount requirement and what is not compulsory are summarized in from how many people are work rules compulsory, and what is not. Read together with opening a medical clinic and labor, which centers on on-call/night duty and nurses' working styles, the key points for medicine and dentistry each come into view.

Who handles labor, the opening notification, property, and tax?

Opening a dental clinic or dental lab divides by qualification, each a separate contract.

What to do	Main person in charge
Work rules and shift design, social/labor insurance application and procedures, payroll	Shakai Hoken Roumushi (our office)
Support for the clinic opening notification and dental lab opening notification (public health center)	Gyoseishoshi (or the director themselves)
Tax on opening, tax return	Tax accountant
Brokerage and important-matters explanation for the clinic/lab property	Real estate agent

The clinic and dental lab opening notifications can be connected to 四葉行政書士事務所 and the property to 四葉不動産, but 四葉行政書士事務所 and 四葉不動産 are separate, independent entities from our office, and the Shakai Hoken Roumushi work, the Gyoseishoshi work, and the real estate work are contracted separately (we do not take them on under one engagement). Our office does not receive referral fees. The basis for the opening notifications (the Medical Care Act and the Dental Technicians Act) is referred to only, and the procedures themselves are done by a Gyoseishoshi or the director.

四葉社会保険労務士事務所 can advise on the social insurance test for part-time/shorter-hours dental hygienists and assistants, technicians' working hours, Article 36 agreements and premium wages, and preparing work rules. Fees are summarized in the fee schedule.

Frequently asked questions

Q. We're a sole-proprietor dental clinic — do we not enroll in social insurance even with five or more staff?
A. No, you do enroll. For health and pension, the medical business is among the statutory applicable industries, so even a sole proprietorship becomes a compulsorily applicable workplace once it has five or more regular staff. Note this is the reverse of service businesses such as barber/beauty, which are not compulsory even with five or more staff as a sole proprietorship. A corporation is compulsory even with the director alone.

Q. I want to keep a dental hygienist part-time within the dependent limit — up to how many hours do they not enroll in social insurance?
A. Compared with a regular worker, if both prescribed weekly hours and monthly working days are under three-quarters, they do not enroll as a rule. But if the workplace is a specified applicable workplace, they become subject under conditions such as 20 or more weekly hours and a monthly wage of 88,000 yen or more. The firm-size requirement expands in stages, and the 88,000-yen wage requirement is set to be abolished in October 2026, so judge by the latest requirements.

Q. Do dental lab technicians need overtime pay?
A. An employed technician is subject to the Labor Standards Act's working hours and premium wages as they are. Working beyond 8 hours a day or 40 hours a week requires concluding and filing an Article 36 agreement, and premium wages are paid for overtime, late-night, and holiday work. Overtime pay is not waived "because they're craftsmen" or "because it's like subcontracting." Even on a subcontract form, if the reality is judged to be employment, the same treatment applies.

Q. Are work rules required at a dental clinic with five staff?
A. Preparation and filing become compulsory from a workplace regularly using ten or more, so with five they are not compulsory. However, notice of working conditions is required from the first worker, and harassment prevention and measures under the Childcare and Family Care Leave Act are compulsory regardless of headcount. Even where not compulsory, the more a dental clinic mixes shorter-hours and part-time staff, the more stable operation becomes when shift and leave rules are put into writing.

Sources

• Health Insurance Act (Act No. 70 of 1922) Article 3(3) and Employees' Pension Insurance Act (Act No. 115 of 1954) Article 6: corporations are compulsory even with one director; individual workplaces are compulsory with five or more regular staff. The applicable industries include "the treatment of disease, midwifery and other medical business" and "the manufacture, processing… business," while service businesses such as barber/beauty are excluded (confirmed against the Japan Pension Service "Applicable workplaces and insured persons" and the list of compulsorily applicable industries for health insurance; accessed 21 September 2026)
• Coverage expansion of social insurance for short-time workers: the three-quarters test; at a specified applicable workplace, 20 or more weekly hours, monthly wage of 88,000 yen or more, expected employment over two months, and not a student. The firm-size requirement is 51 or more insured persons, expanding to 36 or more from October 2027. The 88,000-yen wage requirement is set to be abolished in October 2026 (Ministry of Health, Labour and Welfare "Coverage Expansion special site" and the Japan Pension Service; accessed 21 September 2026)
• Employment Insurance Act (Act No. 116 of 1974) Articles 4 and 6: workers with 20 or more weekly hours, etc., are insured; 10 or more from October 2028
• Labor Standards Act (Act No. 49 of 1947): Article 15 (notice of working conditions), Article 32 (working hours), Article 36 (overtime/holiday work), Article 37 (premium wages), Article 89 (obligation to prepare/file work rules with ten or more regularly)
• Basis for the opening notifications: the Medical Care Act (clinic opening notification/permission) and the Dental Technicians Act (dental lab opening notification). This article refers to them only; the procedures themselves are done by a Gyoseishoshi or the opener
• All provisions confirmed on 21 September 2026 via e-Gov and each agency's published materials. Firm-size and wage requirements and rates are revised, so confirm the latest with the Japan Pension Service and the Ministry of Health, Labour and Welfare

This article does not decide whom to consult. The application and procedures of social and labor insurance, work rules, and payroll are the work of a Shakai Hoken Roumushi. The clinic and dental lab opening notifications go to a Gyoseishoshi or the director, opening tax to a tax accountant, and property brokerage to a real estate agent — each contracted separately as separate, independent entities. Our office does not receive referral fees. For fees when consulting 四葉社会保険労務士事務所, see the fee schedule; for frequently asked questions, see the FAQ.

This article is general information. Individual judgments, such as the social insurance test for part-timers or the treatment of working hours, are made by a qualified professional after a consultation. Written by Joji Uramatsu (Shakai Hoken Roumushi, Gyoseishoshi, Registered Real Estate Transaction Specialist).