- What counts as remuneration
- Why commuting allowances still count
- Where base pay and allowances differ
- Five settings every pay item needs
The short answer
Health insurance and pension premiums are calculated from the standard monthly remuneration, and what counts as remuneration is decided by substance. Housing and commuting allowances paid with salary are included. So "200,000 base plus a 20,000 housing allowance" and "220,000 base" are different wage designs, but for social insurance both are, as a rule, 220,000 of remuneration.
Standard monthly remuneration
Premiums are not a rate applied to each month's pay. Monthly remuneration is placed into one of a set of grades, and the rate is applied to that grade. The Japan Pension Service defines remuneration as everything received regularly in return for work and used for normal living — including benefits in kind such as commuter passes, meals and housing. Its examples include base pay, role allowances, family allowances, commuting allowances, housing allowances and early-start overtime pay.
One-off payments, and bonuses paid three times a year or less, are not monthly remuneration; bonuses are charged separately as a *standard bonus amount*.
Why these allowances count
Both are paid every month under company rules, so they are regular payments for work. The commuting allowance is the classic trap: because it can be non-taxable for income tax, people assume it is outside social insurance too. The Japan Pension Service says a commuting allowance set out in the pay rules is remuneration — including one paid for several months at once (check with the pension office how to spread it across the months).
Non-taxable for income tax, yet remuneration for social insurance: that difference is where most mistakes happen.
Where the two designs actually differ
For social insurance, both are 220,000. The difference shows up elsewhere: in the hourly base for overtime, and in bonuses, retirement pay or raises calculated as multiples of base pay.
Settings every pay item needs
- Income tax: taxable, non-taxable, or partly
- Social insurance: remuneration or not
- Labour insurance: wages or not
- Overtime: in the premium-pay base or not
- Frequency: monthly, one-off, or bonus
Summary
Remuneration is judged by substance. Monthly housing and commuting allowances count, even when non-taxable. Decide each item's treatment up front, and check individual cases with the pension office or a specialist.