JP workers' compensation (rosai) premium — 54 industries × FY2026 rates

Industry category and payroll reveal business scale and sector

The two inputs — industry subcategory and annual gross wages — reconstruct the type of business and its approximate headcount or revenue range. A user entering ‘construction, other’ with ¥100M annual wages is describing a mid-size construction primary contractor with a recognisable labour-cost profile. That combination identifies a commercial target for occupational-injury insurance (労災上乗せ保険), safety-equipment suppliers, social insurance advisors (社会保険労務士), and HR outsourcing firms.

Workers’ compensation calculators offered by payroll-software vendors and labour-law advisory sites see their user base as employers and their payroll administrators — the people responsible for 年度更新 filing. Input data that reveals an employer’s industry and payroll scale is the entry point for sales of additional employer-facing products. A tool used for a quick cross-check before the June annual filing can produce a durable server record of a company’s approximate size and sector.

54 industry rates as JavaScript constants — no lookup required

Workers’ compensation rates are statutory constants revised every three years by MHLW based on industry incident data. The post-FY2024 rates for all 54 industry subcategories — ranging from 2.5/1000 (finance / telecom / instruments) to 88/1000 (metal and coal mining) — are loaded as a JavaScript object at page load. The premium formula is simply annual_wages × rate. No server call is required at any point. The same rates apply through FY2025 and FY2026; the next revision is expected in FY2027. Open DevTools Network and change the industry or wage figure — nothing fires after the initial page load.

Merit rating: when the standard rate does not apply

Employers with 100 or more workers — or 20 to 100 workers meeting specific revenue thresholds — are subject to the merit rating system, which adjusts the standard rate by up to ±40% based on the past three years’ injury and illness record. Construction sites have a separate aggregate merit system. This tool uses standard rates only; the merit-adjusted rate appears on the labour-standards-office notification that accompanies the annual update filing. For employers subject to merit rating, use this tool as a rough benchmark and apply the notified rate for the actual filing calculation.

Annual update filing (June–July) and combining with employment insurance

Labour insurance (rosai + koyo) is filed and paid together at the annual 年度更新 from June 1 to July 10. The filing reconciles the prior-year actual premium (actual wages × rate) against the provisional payment made the previous year, then pays a new provisional premium for the current year. Running this tool for the rosai portion and koyo-hoken-jp for the employment-insurance employer share gives a combined labour-insurance estimate before the window opens. The separate social-insurance employer share (health + pension) is handled by kenpo-kyokai-jp — all three stay browser-only. For years with unusually high bonus payments that inflate total wages significantly above the prior year’s estimate, the reconciliation payment can be large.

Nine-category / 54-subcategory structure and the rate-revision rationale

Workers’ compensation rates are set under Workers’ Accident Insurance Act Article 32-3 based on the past three years of injury-incidence rates (per-mille: workplace casualties / average workforce × 1,000), revised every three years (source: MHLW rate-revision notice). The nine top-level categories are: (1) forestry 60/1000; (2) fisheries 9–18/1000; (3) mining 26–88/1000 (metal and coal highest); (4) construction 9–62/1000 (quarrying highest); (5) manufacturing 2.5–26/1000; (6) transport 4–9/1000; (7) electricity/gas 3/1000; (8) other — commerce, finance, communications — 2.5–13/1000; (9) ship-owner 47/1000. The spread between the lowest (finance, insurance, telecoms) and highest (metal mining) is about 35×.

The 54-subcategory split matters in practice; misclassification triggers labour-standards-office inquiries at the annual update. Within manufacturing, food processing (2.5/1000) is well below chemicals (4/1000) and metal products (10/1000). Construction breaks into civil engineering (16/1000), building work (9.5/1000), and existing-building equipment installation (12/1000), each with its own rate. This tool’s nine-category → 54-subcategory drill-down mirrors this hierarchy. Mixed businesses (e.g., manufacturing plus in-house delivery) should select the principal activity per MHLW notification — the dominant business categorisation governs.

Special enrolment for SME owners, sole-trader contractors, and overseas postings

The basic rosai system covers only ‘workers’ — owners, directors, and self-employed sole traders are excluded. A special enrolment regime covers owners and self-employed contractors whose work resembles employee labour closely enough to merit equivalent protection (source: MHLW special enrolment for workers’ comp). SME-owner special enrolment is available for businesses with up to 300 employees (50 for finance, insurance, real-estate, retail; 100 for service businesses), enrolled through a labour-insurance administrative association (労働保険事務組合). The owner can self-select a benefit basis amount of JPY 3,500–25,000 per day, with the rate applied being the standard rosai rate for the industry.

Construction sole-trader contractors — independent carpenters, plasterers, others working without employees — enrol via a union or administrative association at a standard 18/1000. Overseas-posting special enrolment covers Japanese employees seconded abroad, with the home-country employer handling enrolment. These special premiums are outside this tool’s scope; quotes come from the relevant administrative association or union. The cost-benefit case for special enrolment is strong — premiums run a few tens of thousands of yen annually while injury or fatality benefits reach the millions or tens of millions, so eligible owners and self-employed contractors are typically advised to enrol.