How the rules for part-time and fixed-term employment change in October 2026 — notice at hiring and differences in treatment

In short: From 1 October 2026, when hiring a part-time or fixed-term worker, the matters to be stated in the notice of working conditions will newly include "the fact that the worker may request an explanation of the content of, and reasons for, any difference in treatment from regular employees." However, what a company really needs to prepare is not just the wording on a form. The essence is to use this revision as an opportunity to reach a state where you can explain "why this difference exists" for the differences in treatment between your regular and non-regular employees.

From 1 October 2026, the three points a company should check are:

1. Notice at the time of hiring: whether the affected part-time or fixed-term workers are clearly told that they may request an explanation
2. Differences in treatment from regular employees and the reasons: whether you are in a state where you can explain the differences
3. Consistency among work rules, wage regulations and actual practice: whether the documents and the reality match

Every time the law changes, employers must keep track of employment contracts, work rules, wage regulations, payroll, social insurance and more — simply chasing "what exactly should we change?" is already a heavy burden. This article explains what changes on 1 October 2026, and focuses on how to put the "day-to-day employment management" of explaining differences in treatment in order, rather than a mere change of forms.

What changes on 1 October 2026?

To improve the treatment of part-time and fixed-term workers (referred to below as "part-time/fixed-term workers"), the enforcement regulations (ministerial ordinance) and the notifications for the employment management guidelines and the equal-pay-for-equal-work guidelines are being revised, and come into effect and apply from 1 October 2026. Let us organise the changes into three layers: what changes this time, what has existed for some time, and what is worth checking on this occasion.

Aspect	Before the revision (to September 2026)	After the revision (from 1 October 2026)
Notice at the time of hiring	State the statutory matters in the notice of working conditions	Add "the fact that the worker may request an explanation of differences in treatment" and state it
Explanation of differences in treatment	The duty to explain itself has existed since April 2020	The right to request an explanation is made known to workers at the time of hiring
Approach to the treatment covered	Certain treatment organised under the equal-pay-for-equal-work guidelines	The revised guidelines and employment management guidelines add and clarify the approach to each item of treatment and the measures employers should take

The key point is that the duty to explain differences in treatment does not suddenly begin in October 2026. The duty to explain already exists, and this revision centres on requiring employers to tell workers, at the time of hiring, that they may request an explanation. It is important not to confuse the two.

Who is covered?

The workers covered are part-time workers (short-time workers) and fixed-term workers. There is no exemption based on company size: an employer that employs short-time workers or fixed-term workers is covered. Confirm this by whether a person falls under the legal definition, not by labels such as "part-timer" or "casual worker."

At the time of hiring, "the fact that the worker may request an explanation of differences in treatment" is added to the matters to be stated in writing or by other means, in addition to the existing statutory matters to be stated (such as the term of the labour contract, place of work, duties, wages and working hours). In practice, you will reflect this in the model notice of working conditions published by the Ministry of Health, Labour and Welfare, and in similar documents.

What does "may request an explanation" mean?

Under Article 14 of the Part-Time and Fixed-Term Employment Act, when a worker requests an explanation of the content of, and reasons for, any difference in treatment from regular employees, the employer has a duty to explain. This revision adds, to the matters to be stated at the time of hiring, the fact that an explanation may be requested under Article 14, paragraph 2.

In other words, from the worker's perspective, the right to ask the company "why is my treatment different from that of regular employees?" is now made clear at the time of hiring. From the company's perspective, being able to explain when asked is the premise.

As for the method of explanation, oral explanation using materials is the basic approach, and providing an easy-to-understand document that covers all the necessary matters is also acceptable. Separately, keeping an internal record of when, to whom and what was explained is useful practice for preventing later misunderstandings (see below).

A difference in treatment does not automatically mean it is illegal

Here, the point not to misunderstand is that a difference in treatment is not automatically illegal. What Article 8 of the Part-Time and Fixed-Term Employment Act prohibits is unreasonable differences in treatment.

Whether a difference in treatment is unreasonable is judged comprehensively in light of the nature and purpose of the treatment in question, taking into account the content of the duties, the degree of responsibility, the scope of changes in duties and the range of reassignment, and other circumstances. Even where the name of an "allowance" is the same, the difference may be reasonable if its purpose or the range of recipients differs. It is a mistake to judge legality or illegality by the name of an allowance alone. Whether a particular difference in treatment is lawful is beyond the scope of this article and requires confirmation by a qualified professional.

Why is it hard for the voice of part-time workers to reach the owner?

Alongside confirming the system, there is one more point you should not overlook. Sometimes the dissatisfaction on the side of part-time and fixed-term workers does not sufficiently reach the owner. In day-to-day work, there may be opportunities to hear from regular employees and managers about how part-timers work, but there is not necessarily much opportunity for the owner to hear directly how part-time workers feel about differences in treatment.

Within an organisation, while an information route of regular employees → managers → owner exists on a daily basis, in a company where the route of part-time workers → owner is weak, dissatisfaction may have already accumulated by the time questions about differences in treatment surface. This bias in information can delay noticing dissatisfaction with treatment.

If questions remain unresolved, they may go beyond being raised internally and develop into consultations with the Labour Bureau or dispute-resolution procedures, or — depending on the individual case — into disputes including litigation.

That is why the October 2026 revision is not "done once you add a line to the notice." It should be taken as an opportunity to review treatment once, not only from the voice of regular employees but also from the perspective of part-time workers.

Is it enough to just fix the notice?

No. The notice is "a document handed over at the time of hiring," but actual treatment is determined by the work rules, wage regulations, employment contracts and payroll practices. Even if the notice says "you may request an explanation," you will be in trouble when asked if the substance — the differences in treatment — has not been organised.

At a minimum, cross-check the following three:

1. Notice of working conditions: whether the matters to be stated are complete and the form is up to date
2. Employment contract: whether it contradicts the notice
3. Work rules and wage regulations: whether the provisions on the treatment of regular and non-regular employees match the reality

For the obligation and arrangement of work rules, see from how many employees are work rules mandatory, and what is not mandatory. The notice at the recruitment stage (job advertisement) is covered separately in what must be written in a job advertisement.

How to organise differences in bonuses, retirement allowances, various allowances and leave

In this revision, the items to consider when comparing with regular employees, and the approach to judging them, have been added or clarified in the equal-pay-for-equal-work guidelines and the employment management guidelines for the following items.

• Bonuses
• Retirement allowances
• Various allowances such as accident-free allowances, family allowances and housing allowances
• Welfare facilities
• Sick leave
• Summer and winter leave, commendations and the like

The basic approach to organisation is to clarify, one by one, "what is this treatment provided for?" However, simply putting the purpose of payment into words does not make a difference in treatment reasonable. You need to organise it in light of the content of the duties, responsibility, the scope of changes in duties and reassignment and other circumstances, and the nature and purpose of the treatment in question.

Note that social insurance (the "1.06 million yen wall") is a separate system from working conditions and treatment. To avoid confusion, for social-insurance coverage see the 1.06 million yen wall is abolished in October 2026 — what a business owner should do.

Documents a company should prepare when asked for an explanation

When asked for an explanation, oral explanation alone is hard to convey and can leave differences in understanding. Having the following documents in order makes explanation easier.

• Documents showing the content of duties, responsibility and scope of reassignment (job descriptions, organisation charts, etc.)
• A list of wages, allowances, leave and welfare benefits for regular and non-regular employees
• Notes organising the reasons for differences in treatment (purpose of payment, recipients, basis for the amount)
• Work rules, wage regulations and employment contracts (the latest versions)
• A form for recording the date, content and recipient of the explanation

The method of explanation required by law (oral explanation using materials is the basic approach) should be separated from keeping an internal record of the process of explanation. In practice, recording when, to whom and what was explained helps prevent later misunderstandings.

Checklist for owners before the effective date

By 1 October 2026, check in the following order.

1. Identify the affected part-time and fixed-term workers
2. Check the matters to be stated in the notice of working conditions (including "the fact that an explanation may be requested")
3. Check the consistency of employment contracts, work rules and wage regulations
4. List differences in bonuses, retirement allowances, various allowances, leave, sick leave and so on, and organise the reasons
5. Set rules for who responds, what to explain and how to record when an explanation is requested

What can 四葉社会保険労務士事務所 organise?

It is a considerable burden for an owner to keep following every regulatory change on their own. 四葉社会保険労務士事務所 values organising "what this company should check," rather than merely explaining the revision itself. We organise the differences in treatment and their reasons from documents, regulations and actual practice, and clarify which points a qualified professional should confirm. The first consultation (up to 60 minutes) is free. For fees, see the fee schedule.

Frequently asked questions

Q. From October 2026, do I need to redo the notice of working conditions?
A. Because the matters to be stated at the time of hiring will increase, newly hired part-time and fixed-term workers will need a notice that includes "the fact that they may request an explanation of differences in treatment." Even for existing workers, we recommend checking the consistency of the notice, employment contract and work rules.

Q. Is it illegal if part-time workers receive different allowances from regular employees?
A. Not necessarily. What is prohibited is unreasonable differences in treatment. What matters is whether you can explain the purpose of payment in light of the content of duties, responsibility, the scope of reassignment and so on. Individual judgments require confirmation by a qualified professional.

Q. How far must differences in treatment be explained?
A. When a worker requests an explanation, the employer has a duty to explain the content of the treatment, the matters considered in determining it, and the content of and reasons for any difference in treatment from regular employees. Having documents and records ready is the premise.

Q. Do the work rules also need to be changed?
A. Work rules must be drawn up and filed if the headcount requirement is met, but separately from that, check that the actual treatment does not diverge from the regulations. To explain differences in treatment, it is important to keep the provisions of the regulations consistent with actual practice.

Sources

• Act on Improvement, etc. of Employment Management for Part-Time Workers and Fixed-Term Workers, Article 8 (prohibition of unreasonable differences in treatment) and Article 14 (duty to explain differences in treatment). Under the revision that takes effect and applies from 1 October 2026, "the fact that an explanation may be requested under Article 14, paragraph 2" is added to the matters to be stated in the notice of working conditions at the time of hiring.
• Ministerial Ordinance Partially Amending the Ordinance for Enforcement of the Act on Securing the Proper Operation of Worker Dispatching Undertakings and Improved Working Conditions for Dispatched Workers and the Ordinance for Enforcement of the Act on Improvement, etc. of Employment Management for Part-Time Workers and Fixed-Term Workers (Ministry of Health, Labour and Welfare Ordinance No. 87 of 2026; promulgated on 28 April 2026, in force from 1 October 2026).
• Notice Partially Amending the Guidelines on Measures, etc. That Employers Should Take for the Improvement, etc. of Employment Management for Part-Time Workers and Fixed-Term Workers (Ministry of Health, Labour and Welfare Notification No. 202 of 2026; promulgated on 28 April 2026, applied from 1 October 2026). The content of the measures for the improvement of employment management is revised.
• Notice Partially Amending the Guidelines on the Prohibition, etc. of Unreasonable Differences in Treatment of Part-Time and Fixed-Term Workers and Dispatched Workers (Ministry of Health, Labour and Welfare Notification No. 203 of 2026; promulgated on 28 April 2026, applied from 1 October 2026). Under this revision to the so-called equal-pay-for-equal-work guidelines, the treatment of and approach to judging bonuses, retirement allowances, accident-free allowances, family allowances, housing allowances, welfare facilities, sick leave, summer and winter leave, commendations and the like are clarified.
• The content of the revision, the model notice of working conditions, the old/new comparison tables and the Q&A have been confirmed in primary sources such as the Ministry of Health, Labour and Welfare's "equal pay for equal work" page (as of August 2026). For details of the implementation, please check the latest revised ordinance, notifications and Q&A.
• Whether a difference in treatment is reasonable is judged comprehensively in light of the nature and purpose of the treatment in question, taking into account the content of the duties, the degree of responsibility, the scope of changes in duties and reassignment and other circumstances. This article is limited to a general explanation.

This article does not decide whom you should consult. Preparing work rules, wage regulations, the notice of working conditions and employment contracts, and organising differences in treatment, are the work of a Shakai Hoken Roumushi. Tax matters (the tax treatment of allowances) are the domain of a tax accountant, and individual disputes and litigation are the domain of a lawyer. 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. Whether the system applies and whether a particular difference in treatment is lawful are determined by a qualified professional after a consultation, in light of the latest primary sources (Ministry of Health, Labour and Welfare, e-Gov, etc.) and individual circumstances. Written by Joji Uramatsu (Shakai Hoken Roumushi, Gyoseishoshi, Registered Real Estate Transaction Specialist).