The care worker treatment-improvement addition — how do you revise the wage rules? The line between the addition and labour

Bottom line first: The care worker treatment-improvement addition (kaigo shokuin tou shogu kaizen kasan) cannot be maintained just by drawing down the money. You must write into the wage rules and work rules "which wage, to whom, and how much" the funds the addition adds are distributed as, be able to show the plan and the results, and only then can it be claimed and maintained. Designing the wage system is for the Shakai Hoken Roumushi; filing the plan and result reports to the designating authority is for the Gyoseishoshi; tax is for the tax accountant.

How you raise wages — base-up or lump sum — changes both where it is written in the work rules and how it feeds through to social-insurance premiums. We set out, from the labour side, where to revise so the requirements are met and the result report is not rejected.

The choice of the addition's category and whether a notification can be filed change by office and by year, so this article does not conclude them. Individual determinations are made by a qualified professional after a consultation.

Why does drawing the treatment-improvement addition require revising the wage rules?

The care worker treatment-improvement addition, since June 2024, unifies the former three additions (the care worker treatment-improvement addition, the specified treatment-improvement addition and the base-up support addition). The requirements fall broadly into three, and each asks both "what the rules say" and "the record of having paid accordingly".

Requirement	Outline	Where it lands on the labour side
Career-path requirement	Appointment requirements and a wage structure, training opportunities, a pay-rise mechanism by experience and qualifications	Work rules, wage rules, career-path rules
Monthly wage-improvement requirement	Making a set proportion or more of the addition's wage improvement by base pay or an allowance paid each month	Wage rules, wage ledger
Workplace-environment requirement	Efforts to improve the workplace environment	Work rules, internal rules, records

The career-path requirement asks for a "wage structure" and a "pay-rise mechanism". Matters concerning pay rises are, under Article 89(2) of the Labor Standards Act, items that must be written into the work rules (absolutely necessary items). In other words, to meet the addition's requirements, the work rules and wage rules must already set out how pay rises and wages are decided. Left as a verbal promise, it stops at the entrance to the addition. The relation between staffing standards, the addition and wages in disability welfare is set out in Staffing standards and labour for child development support and after-school day services.

Whose job is "filing the addition" and "designing the wage system"?

The treatment-improvement addition splits by responsible party across the process. Get this wrong and an unqualified person steps into an exclusive practice.

Issue	In charge
Designing the wage structure and pay-rise mechanism, preparing wage rules and work rules, designing the distribution of the wage-improvement amount, checking the effect on social insurance	Shakai Hoken Roumushi (this office)
Preparing and filing the plan and result reports to the designating authority (municipality / via the insurance federation)	Gyoseishoshi
Accounting for the addition income and the corporation's tax	Tax accountant

Preparing and filing the plan and result reports is an administrative procedure toward the designating authority and is Gyoseishoshi work. 四葉行政書士事務所 is a business entity independent of this office; where needed we introduce it under a separate contract that you conclude directly, and this office takes no referral fee. The split of "which to ask, the Shakai Hoken Roumushi or the Gyoseishoshi" is set out in Is the treatment-improvement addition asked of the Shakai Hoken Roumushi or the Gyoseishoshi. This article narrows to the Shakai Hoken Roumushi side of that work — how to revise the wage rules.

Base-up or lump sum — which distribution meets the requirement?

The monthly wage-improvement requirement asks that a set proportion or more of the addition's wage improvement be made by base pay or an allowance paid each month (base-up and the like). Where it cannot all be distributed by base-up, combining other allowances or a lump sum is permitted, but a design that "distributes the whole as one annual lump sum" does not meet the requirement.

How you raise wages changes where it is written in the work rules.

Method of distribution	Position in the work rules and wage rules	Basis
Raising base pay or a monthly allowance (base-up, pay rise)	Matters on determining, calculating and raising wages = must be written	Labor Standards Act Article 89(2) (absolutely necessary item)
Payment by lump sum or bonus	Temporary wages etc. = written if you set a rule	Labor Standards Act Article 89(4) (relatively necessary item)
Adding to retirement pay	Written if you set a retirement-pay rule	Labor Standards Act Article 89(3)-2 (relatively necessary item)

To meet the monthly wage-improvement requirement, at least a set part must be raised as the "monthly wage" of item 2. So revising the wage rules cannot be avoided. The specific proportion of distribution per category changes by year and category and is not covered here (unverified).

How do social-insurance premiums change when you raise wages?

Raising monthly wages by base-up raises the standard monthly remuneration, and the health-insurance and employees'-pension premiums (labour and management split them, so the employer's share too) can rise. The dividing line is whether the raise is a "change in fixed wages".

Way of raising	Effect on standard monthly remuneration
Raising base pay or a monthly allowance (change in fixed wages)	If the three-month average from the change month rises by two grades or more and each month's payment-basis days are 17 or more, a revised determination (monthly-change notification) applies in the fourth month. Premiums rise
An annual or semi-annual bonus or lump sum	There is a premium on the bonus as the standard bonus amount, but the monthly standard remuneration (the monthly premium) does not rise

A revised determination applies only when three things coincide: a change in fixed wages, a two-grade-or-more difference in the three-month average, and 17 or more payment-basis days each month (11 or more for short-hour workers) (Health Insurance Act Article 43; Employees' Pension Insurance Act Article 23). The difference from the annual regular determination (decided on April–June remuneration, applied from September) is set out in How the regular determination and the monthly-change notification differ. Because a higher standard monthly remuneration also raises the future pension, "higher premium = loss" does not always hold. On enrolment judgments for part-time and short-hour staff, see also When you hire for short hours, what happens to social insurance.

To avoid rejection at the result report, what should the work rules state?

The treatment-improvement addition is a mechanism for showing, in the result report, that wage improvement was carried out as planned. Where the rules and reality diverge, it is rejected here and repayment can be demanded. On the labour side, what to set out in writing in advance is the following.

• State clearly in the wage rules which wage item (base pay, a treatment-improvement allowance, etc.) the addition's wage improvement is made through
• Write in the rules who is covered (covered roles, the thinking on distribution) and make it traceable in the wage ledger
• Show the pay-rise mechanism and appointment requirements in the career-path rules
• Keep the actual payment in the wage ledger and pay slips, matching the plan

The thread "the money the addition brought in was paid, to that worker, as the rules said" being joined into one line across the rules, the wage ledger and the pay slip is the core of the result report. The duty to draw up and file work rules itself arises at a workplace ordinarily employing ten or more workers (Labor Standards Act Article 89). The mandatory work rules and the rules arranged for the addition have different purposes, and even with fewer than ten there are many cases where wage rules are arranged for the addition.

Who should handle the labour, the addition's notifications and the tax?

Around the treatment-improvement addition, the responsible entity splits.

Issue	In charge
Preparing wage rules, work rules and career-path rules, designing the distribution of the wage-improvement amount, social-insurance procedures	Shakai Hoken Roumushi (this office)
Preparing and filing the plan and result reports to the designating authority	Gyoseishoshi
Accounting for addition income and the corporation's tax	Tax accountant
Registration relating to the corporation and its officers	Judicial scrivener

Preparing the plan and result reports to the designating authority is Gyoseishoshi work, and 四葉行政書士事務所 is a business entity independent of this office. Accounting and tax for addition income are matters we connect you with a tax accountant for, and registration a judicial scrivener. Where needed, we introduce them under a separate contract that you conclude directly, and this office takes no referral fee.

Consultations are free of charge. Fees are set out in the fee schedule; see also our services and how a consultation proceeds.

Frequently asked questions

Q. If we only want to draw the addition, need we not revise the wage rules?
A. The addition's requirements (career-path, monthly wage-improvement, workplace-environment) presuppose that the wage structure, the pay-rise mechanism and the content of the wage improvement are arranged as rules. In particular, matters on pay rises are an absolutely necessary item of the work rules under Article 89(2) of the Labor Standards Act. Where the rules do not match reality, you stumble at the claim or the result report. Arranging the rules cannot be avoided, for maintaining it as well as for drawing it.

Q. May we distribute the whole as one annual bonus?
A. The monthly wage-improvement requirement asks that a set proportion or more of the addition's wage improvement be made by base pay or an allowance paid each month. Topping up with a lump sum where base-up alone is short is permitted, but a design that raises no monthly wage and distributes the whole as one annual lump sum does not meet the requirement. The specific proportion changes by year and category, and this article does not conclude it.

Q. Do the company's social-insurance premiums also rise when we raise wages?
A. Raising base pay or a monthly allowance can trigger a revised determination (monthly-change notification) as a change in fixed wages. If the three-month average from the change month raises the standard monthly remuneration by two grades or more and each month's payment-basis days are 17 or more, it is revised in the fourth month and the labour-and-management-split premium rises. An annual or semi-annual bonus carries a premium on the bonus but does not raise the monthly standard remuneration itself.

Q. Can we ask the Shakai Hoken Roumushi to prepare the plan and result reports too?
A. Preparing and filing the plan and result reports to the designating authority is Gyoseishoshi work. What this office (Shakai Hoken Roumushi) takes on is preparing the wage rules, work rules and career-path rules, designing the distribution of the wage-improvement amount, and checking the effect on social insurance. The filing is accepted by 四葉行政書士事務所 as a separate business entity, under a separate contract. Which to ask for what is set out in the article on splitting the Shakai Hoken Roumushi and the Gyoseishoshi.

Basis for this article

• Labor Standards Act (Act No. 49 of 1947) Article 89 — the duty of an employer ordinarily employing ten or more workers to draw up and file work rules. Item 2 = the determination, calculation and payment of wages (excluding temporary wages), the cutoff and payment timing, and matters on pay rises (absolutely necessary item). Item 3-2 = matters where a retirement-pay rule is set. Item 4 = matters where a rule on temporary wages etc. (excluding retirement pay; bonuses and lump sums) is set (relatively necessary items). Confirmed on e-Gov and Rodo.co.jp's "labour-law search" (accessed 25 August 2026)
• Health Insurance Act Article 43; Employees' Pension Insurance Act Article 23 — the revised determination (a change in fixed wages, a two-grade-or-more difference between the standard monthly remuneration from the three-month average thereafter and the previous one, and 17 or more payment-basis days each month [11 or more for short-hour workers], applied from the fourth month). Confirmed at the Japan Pension Service "revised determination (monthly-change notification)" (accessed 25 August 2026)
• Health Insurance Act Article 41; Employees' Pension Insurance Act Article 21 — the regular determination (deciding the standard monthly remuneration on remuneration paid in April, May and June, applied from that September to the following August)
• Care worker treatment-improvement addition — from June 2024, unifying the care worker treatment-improvement addition, the specified treatment-improvement addition and the base-up support addition. The requirements are the career-path requirement (I–V), the monthly wage-improvement requirement (a set proportion or more of the addition's wage improvement by base pay or a monthly allowance, with a lump sum etc. combinable for any shortfall), and the workplace-environment requirement. Confirmed from Ministry of Health, Labour and Welfare materials and leaflets (accessed 25 August 2026)
• The specific addition rates and distribution proportions per category (I–IV and the transitional category), and the individual application of the review from fiscal 2026 onwards, change by office and by year and are not covered here (unverified)
• The practical forms and reception practice of municipalities and the insurance federation depend on each designating authority's guidelines and are not covered here (unverified)

This article is general information. Individual determinations are made by a qualified professional after a consultation, in light of individual circumstances. 四葉社会保険労務士事務所 can advise on preparing wage rules, work rules and career-path rules that write in the treatment-improvement addition requirements, designing the distribution between base-up and a lump sum, and checking the effect of wage improvement on standard monthly remuneration and social-insurance premiums. Preparing and filing the plan and result reports to the designating authority is accepted by 四葉行政書士事務所 as a separate business entity, each contracted separately. Accounting for addition income and the corporation's tax are matters we connect you with a tax accountant for, and registration a judicial scrivener. If a different professional is needed, each is contracted separately, and there is no referral fee. Frequently asked questions are collected in the FAQ. Written by Joji Uramatsu (Shakai Hoken Roumushi, Gyoseishoshi, Registered Real Estate Transaction Specialist).