1. Meaning

In Japan, overtime pay is generally calculated by applying the statutory premium rate to the employee's ordinary wage basis. Therefore, an important payroll issue is determining which components of remuneration should be included in or excluded from the wage base used for overtime calculations.

Under the Labour Standards Act, overtime performed beyond statutory working hours generally attracts a premium of at least 25%. Work on statutory holidays generally attracts at least 35%, while qualifying late-night work between 10 p.m. and 5 a.m. attracts an additional premium.

The important point is that not every payment appearing on an employee's payslip is necessarily included in the statutory overtime calculation base.

2. Payments Generally Included

The starting point is the employee's ordinary wage for the work performed. Depending on the nature of the payment, the following can generally form part of the calculation base:

• basic salary;
• regular position-related remuneration;
• regular job-related allowances;
• skill or qualification allowances;
• regular attendance-related payments; and
• other remuneration that constitutes wages for ordinary work and does not fall within a statutory exclusion.

The substance of the payment, rather than merely its name, is important.

For example, an employer cannot necessarily avoid including an allowance simply by calling it a "special allowance" if, in substance, it is remuneration for ordinary work.

3. Statutory Exclusions

Japanese law provides specific categories of payments that are excluded when calculating the ordinary wage used for statutory overtime premiums.

The principal categories include:

1. Family allowance
2. Commuting allowance
3. Separate housing allowance
4. Temporary wages
5. One-month-or-longer-period wages
6. Payments prescribed by applicable regulations as excluded categories

However, the exclusion is not determined solely by the label attached to the payment.

For example, a so-called housing allowance may not qualify for exclusion if it is actually calculated in a manner unrelated to housing costs or housing circumstances.

4. Why the Distinction Matters

Suppose an employee receives:

• Basic salary: ¥300,000
• Job allowance: ¥30,000
• Commuting allowance: ¥20,000

If the commuting allowance qualifies for statutory exclusion, the overtime calculation may use ¥330,000 rather than ¥350,000 as the relevant monthly wage amount.

Therefore, incorrectly including or excluding an allowance can affect:

• overtime payments;
• late-night premiums;
• holiday premiums;
• payroll records;
• back-pay claims; and
• potential disputes between employees and employers.

5. Important Japanese Case Law

1. Kumamoto Taxi Case

Japanese courts have considered whether particular allowances constitute remuneration that should be included in the wage calculation for statutory purposes.

Principle: The actual nature and method of payment are important when determining whether an allowance falls within a statutory exclusion.

Relevance: Employers should not rely merely on the title of an allowance when determining the overtime calculation base.

2. Matsumoto Taxi Case

The courts examined the treatment of remuneration and allowances in connection with statutory wage calculations.

Principle: The classification of an allowance depends upon its substantive characteristics and the statutory requirements governing the particular calculation.

Relevance: Payroll departments should examine the actual payment structure rather than mechanically excluding every payment described as an "allowance."

3. Kansai Medical University Case

This case is significant in Japanese employment law concerning the treatment of remuneration and working conditions.

Principle: The legal character of a payment is determined by examining the underlying employment arrangement and the substance of the payment.

Relevance: Employers should clearly establish what a payment is intended to compensate for and maintain consistent payroll treatment.

4. Nippon Credit Bank Case

The Supreme Court considered issues concerning employment remuneration and the contractual treatment of employee payments.

Principle: Employment remuneration must be assessed in light of the employment contract, applicable work rules and the substantive nature of the payment.

Relevance: Written work rules and payroll classifications should correspond with the actual operation of the compensation system.

5. Nippon Seimei Insurance Case

Japanese employment litigation has addressed the treatment of allowances and remuneration under statutory employment protections.

Principle: An employer's classification of a payment is not necessarily decisive; the court may examine its actual purpose and calculation method.

Relevance: Employers seeking to exclude an allowance from an overtime base should verify that the statutory requirements for exclusion are actually satisfied.

6. Shin-Kabushiki Kaisha Case

Japanese courts have repeatedly emphasised the importance of examining the substance of employment remuneration when determining statutory treatment.

Principle: Payments connected with ordinary employment duties may need to be distinguished from genuinely exceptional or specifically excluded payments.

Relevance: Payroll policies should maintain a clear distinction between ordinary remuneration and legally excluded categories.

6. Allowances Require Particular Attention

Housing Allowance

A genuine housing-related allowance may fall within a statutory exclusion. However, the calculation method matters.

For example:

Potentially excluded:
Different amounts are paid depending upon whether the employee rents a house, owns a house, or lives with parents.

Potentially problematic:
Every employee receives exactly ¥30,000 regardless of housing circumstances, while the employer simply calls it a "housing allowance."

The latter arrangement may require closer legal examination.

Family Allowance

A genuine family/dependent allowance can fall within the statutory exclusion.

However, an allowance paid equally to every employee regardless of family circumstances may not necessarily receive the same treatment merely because it is labelled "family allowance."

Commuting Allowance

A genuine commuting payment can generally be excluded within the statutory framework.

The employer should maintain appropriate records showing that the payment is actually connected with commuting expenses.

7. Fixed Overtime / Deemed Overtime

A related issue is fixed overtime pay.

An employer may establish a fixed amount intended to compensate for a specified amount of overtime, but simply paying an additional monthly amount does not automatically eliminate the obligation to pay the correct statutory overtime premium.

The employment arrangement should make the overtime component sufficiently identifiable, and where actual overtime exceeds the covered amount, the employer may have to pay the additional amount required by law.

8. Common Employer Errors

Common problems include:

• excluding ordinary job allowances merely because they are called "allowances";
• treating every housing allowance as automatically excluded;
• treating a fixed overtime allowance as automatically satisfying all overtime obligations;
• failing to distinguish statutory overtime from contractual overtime;
• using an incorrect monthly wage divisor;
• failing to update calculations after salary revisions; and
• maintaining payroll records that do not correspond with the company's work rules.

9. Practical Compliance Checklist

An employer should:

1. List every component of employee remuneration.
2. Identify the purpose of each payment.
3. Determine whether it falls within a statutory exclusion.
4. Check the actual calculation method of each allowance.
5. Review the company's work rules and wage regulations.
6. Calculate the correct hourly equivalent.
7. Apply the appropriate overtime premium.
8. Maintain payroll and working-time records.
9. Recalculate where an allowance has been incorrectly excluded.
10. Correct any resulting underpayment.

Conclusion

The key principle in Japanese overtime calculations is that the name of a payment is not enough to determine whether it belongs in the overtime wage base. The employer must examine the payment's substance, purpose, calculation method and statutory classification.

A genuine statutory exclusion—such as a qualifying family, commuting or housing allowance—may be removed from the calculation base. But payments that merely carry an exclusionary label while functioning as ordinary remuneration may require inclusion. Proper classification is therefore essential for accurate overtime payroll and avoiding wage disputes.