Japan Probation Period for Foreigners: What "試用期間" Really Means (And 3 Illegal Terms HR May Try)

Information current as of April 2026 based on MHLW 三菱樹脂事件 precedent summary, MHLW probation duration precedents, Ibaraki Labor Bureau 労基法21条 guidance, and the Supreme Court ruling 三菱樹脂事件 (最大判昭48.12.12).

Foreign hires arriving from at-will jurisdictions — particularly the United States — frequently assume Japanese probation functions the same way: the employer can let you go during the trial period with no cause. This assumption is wrong, and it works against you at two moments. First, when HR presents probation terms that look "softer" than regular employment but are actually identical or stricter on the employer. Second, when you leave the company yourself without realizing probation affects your unemployment benefits and visa status differently from regular service.

The legal definition — 解約権留保付労働契約

Japanese courts classify probation as a "labor contract with reserved termination rights" (解約権留保付労働契約). The framing matters. You are already employed from day one. The employer has reserved an extra termination right that they may exercise during the probationary period, but exercising it is not unilateral or unreviewable.

The Supreme Court established this in 三菱樹脂事件 (最大判昭48.12.12): a company revoked a 試用期間 dismissal after discovering undisclosed student-activist history. The Court ruled the employer could dismiss during probation only for "客観的合理的理由" and "社会通念上相当" — the same standard as regular-employee dismissals, with slight relaxation for facts that only become apparent during probation.

In practice, this means:

• Poor performance with no warnings or improvement opportunity → likely invalid dismissal
• Major skill gaps undisclosed at hiring that materially prevent job performance → may be valid
• Minor personality clashes, single interpersonal issue → likely invalid
• Undisclosed criminal record relevant to the role → likely valid (三菱樹脂 pattern)

Courts routinely reinstate foreigners dismissed during probation when the employer fails to document performance issues, show improvement coaching, or identify the specific contractual failure.

Duration — no statutory max but 1 year is the soft limit

Japan has no hard statutory cap on probation length. Three-month and six-month probations are standard. Some companies try longer — up to a year — and a handful attempt indefinite extensions.

Case law:

• 3-6 months: routinely upheld as reasonable
• 12 months: accepted if the role genuinely requires extended evaluation (e.g., financial adviser, medical resident)
• Beyond 12 months: courts routinely void as abuse of the reserved termination right
• Indefinite extensions: void — probation must have a defined endpoint

The 大隈鐵工所事件 line of cases limits extensions unless specific cause is documented. Automatic "extended at company discretion" clauses without cause are unenforceable.

Conditions during probation — what's legal vs illegal

Lower salary: generally legal

Reduced salary during probation is legal if:

• Clearly stated in the 労働条件通知書 before hire
• Above the applicable 最低賃金 (prefectural minimum wage)
• Not disguised as a demotion (i.e., the post-probation figure is specified too)

Typical pattern: 90% of target salary during probation, rising to 100% on confirmation. Anything more aggressive signals a problematic employer.

Social insurance: mandatory from day one

Here is where many companies break the law. 健康保険 and 厚生年金 enrollment is mandatory from the first day of employment if the eligibility criteria are met (generally ≥30 hours/week at an applicable workplace). There is no "probation exception" in the pension or health insurance statutes.

Some employers tell foreign hires "your shakai hoken starts after probation." This is illegal. Verify your first payslip shows 健康保険料 and 厚生年金保険料 deductions. If they don't, see our guide on forcing employer enrollment.

Fewer benefits: depends

Vacation accrual is tied to statute: 10 days of paid leave after 6 months of continuous service at 80%+ attendance (労基法39条). The 6 months counts from the first day — probation included. Companies trying to delay vacation accrual until "post-probation" are violating 労基法.

Discretionary benefits (family allowance, commuting allowance above statutory tax-free limit, training budget) can legally differ during probation if documented. These are less important than the hard items above.

The 14-day rule — what it actually says

労基法21条 exempts the employer from paying 30-day dismissal notice or 30-day pay in lieu if:

• The employee has been working ≤14 consecutive days, AND
• The employment was not originally contracted for a term ≥2 months

This does not mean dismissal during the first 14 days is "at will." The substantive dismissal standard — 客観的合理的理由 and 社会通念上相当性 — still applies. The 14-day rule only affects the procedural notice requirement.

Practical meaning: If an employer tries to dismiss you on day 10 with no cause, they can skip the 30-day notice — but they cannot legally dismiss you at all without grounds. The dismissal is substantively invalid and reinstatement or settlement is possible.

Foreign workers frequently hear "we're still inside the 14 days so we can let you go without cause." Push back in writing: "I understand 労基法21条 affects the notice period only. What is the substantive reason for termination?"

Probation and visa status — the hidden cost of early termination

If you are dismissed during probation:

• Your 在留資格 remains valid, but the 3-month rule under 入管法22条の4 starts immediately
• File the 14-day 所属機関届出 notification online or at 入管
• Collect documentation from the employer — a 解雇通知書 or 離職票 — stating the reason. You will need this for visa renewal explanations
• Start the job search immediately; 3 months of no authorized activity triggers 在留資格 revocation risk

If you resign during probation:

• Technically voluntary, but document the circumstances in case the resignation was effectively coerced
• Same 14-day and 3-month rules apply
• Unemployment benefits (雇用保険) require 12 months of premium history in the last 2 years — a short probation stint alone usually doesn't qualify

For full visa-side handling: Japan Visa Sponsorship Clauses.

Red-flag probation clauses to reject or renegotiate

Clause	Why it's a problem	What to ask for
"At company discretion, probation may be extended without limit"	Unenforceable beyond a reasonable duration with cause	"Maximum one extension of 3 months with written reason"
"During probation, the company may terminate at any time with 14 days' notice for any reason"	Substantively false — cause still required	Delete "for any reason," require written termination reason
"Social insurance enrollment begins after probation confirmation"	Illegal	Delete; insist on day-one enrollment
"Probationary salary ¥X; standard salary post-probation ¥Y"	Legal IF Y is specified. Red flag if X << Y with vague promotion criteria	Specify measurable criteria for confirmation
"Vacation days accrue only from post-probation start date"	Illegal — 労基法39条 uses first-day-of-employment	Delete; accrue from day one

If you are fired during probation

1. Do not sign anything that looks like a resignation letter (退職届 / 退職合意書) without consulting a lawyer. "Mutual agreement" wording forfeits your ability to challenge the dismissal.
2. Request the dismissal reason in writing — the employer must issue a 解雇理由証明書 on request (労基法22条).
3. File the 14-day 所属機関届出 with Immigration regardless of how the dismissal ends up classified.
4. Document performance feedback you received or didn't receive. Absent prior warnings and improvement opportunities, probation dismissals are usually invalid.
5. Consult a lawyer or the 労働基準監督署 within 30 days. Delay weakens the case.

Next steps: Wrongfully Fired in Japan: Your Rights and How to Fight Back.

The bottom line

Japanese probation is not an escape hatch for employers. The substantive dismissal standard is essentially the same as for regular employees, with only a slight allowance for new-information cases. What probation does give employers is slightly looser procedural notice (labor standards law 14-day rule) and the visible psychological pressure of the trial label.

For foreigners, the biggest risk is not harsh probation dismissals — those are reviewable. It's signing clauses that look boilerplate but contain illegal terms: delayed social insurance, indefinite extensions, no-cause termination language. Catch those before signing. For the full contract framework: Japan Job Contract Guide for Foreigners.