What changes
Under the 2025 pension reform law (Act No. 74 of 2025, promulgated 20 June 2025), the employer-size test for covering part-timers in employees' health and pension insurance is phased out over ten years:
- 1 October 2027: employers with 36 or more employees (currently 51 or more).
- 1 October 2029: 21 or more.
- 1 October 2032: 11 or more.
- 1 October 2035: no size test; every employer is covered.
The other tests stay: 20 hours or more a week, not a student, and employment expected to last more than two months. The 88,000-yen wage test was already abolished on 1 October 2026, so once an employer is in scope, pay level no longer matters.
Separately, from October 2029 newly established unincorporated businesses with five or more staff in any industry must enrol their employees; businesses that already exist at that date are excluded for the time being. Corporations of any size are already fully covered for full-time staff.
Who it applies to
Mainly small entities: a small subsidiary or sales office that today has fewer than 51 insured employees and therefore does not have to enrol its short-hour part-timers. Larger employers are unaffected, as their part-timers are already covered.
Action for employers
- Know which wave you are in. Count your insured employees, confirm the method with your social insurance adviser, and note the date your entity comes into scope.
- Map your part-timers early. Identify who works 20 hours or more a week; each will need enrolment notices from the start date.
- Budget for the cost. The employer pays roughly 15% on top of each newly covered part-timer's pay; a three-year support measure can offset part of the employee share for low earners.
- Consider opting in sooner. Employers below the threshold can extend coverage voluntarily by labour-management agreement, which helps recruitment.
Sources
- Act Partially Amending the National Pension Act and Related Acts (Act No. 74 of 2025).
- Ministry of Health, Labour and Welfare, explanatory materials on the 2025 pension reform law (schedule for the employer-size requirement).