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Certificate of Coverage for Japan: Avoid Double Payments

Certificate of Coverage Japan assignees carry is the document that keeps a temporary posting inside one pension system instead of two.1 The home office issues it, the Japanese employer files it, and the pension office records the exemption that stops the second deduction.12

Confirm current details with official sources

Procedures, fees, and requirements can change. Confirm current details at the Japan Pension Service English pages. This article is general information, not legal, tax, or immigration advice; for your specific case, consult a licensed social insurance labor consultant (sharoushi) before payroll is set.

Overview​

The certificate proves continuing home-country coverage during a qualifying temporary transfer.1 With it on file, the posted worker contributes only at home while Japan exempts the same salary; without it, both systems bill the same months.1

This flow fits temporary postings under a treaty in force, commonly up to five years of initial cover.3 Ordinary local hires fall outside it and join the Japanese system from the start.1

Who issues it in the home country​

The issuer is always the home-country social security office, never the Japan side.1 Form names and channels differ per treaty, so the request must match the worker's coverage state.1

United States postings run through the Social Security Administration request flow for Japan.2 United Kingdom postings run through HMRC abroad channels.4 Other treaty states use their own pension or social security offices under the same principle: the office that holds the worker's home coverage issues the proof.1

Match the request to the coverage state

A worker covered in the United States requests from SSA. A worker covered in the United Kingdom requests from HMRC. Sending the request to the wrong office restarts the clock.24

Japan-side processing​

The transferee hands the issued certificate to the Japanese employer.1 The employer files it with the local pension office and obtains the Japan-side coverage waiver for the posting window.1

Payroll must reflect the waiver once recorded. Enrollment entered before the waiver lands accrues Japan contributions for the gap, which is why employers ask for the certificate during pre-assignment rather than after arrival.1

No certificate markers appear inside the diagram by design; the filing citation sits in the introducing paragraph.1

Duration cap, extension, and conversion​

Typical initial cover runs up to five years, including under the United States agreement.3 Extension beyond the initial window is possible in some treaty cases on request before expiry, but practice varies by bilateral and is never automatic.5

A transfer that exceeds the cap or was open-ended from the start converts to the Japanese system from the cap date.5 The worker then enrolls in 厚生年金 (kōsei nenkin, "Employees Pension") through payroll like any locally covered employee, and posting relief ends.15

Calendar the expiry and the extension request together

An expired certificate without an approved extension restarts Japan enrollment. Diarise both dates at assignment start rather than discovering the gap at year-end reconciliation.5

When the certificate is missing or expired​

Without a valid certificate, the worker contributes to both systems for the uncovered months.1 The Japan-side contributions are not wasted on the spot, but they are also not automatically refunded at payroll.

The remaining prospect is the lump-sum withdrawal at end of stay, which can refund part of the Japan contributions subject to its own month cap and two-year filing deadline.6 That recovery path belongs to the withdrawal guides; this article records it only so assignees understand the cost of a missing certificate.6

Good to know​

Request the certificate before the first Japan payroll​

Payroll enrollment is hard to unwind retroactively. An early request prevents the double-payment window that late paperwork creates.12

An expired certificate does not extend itself​

Expiry without an approved extension ends the waiver on its date. Continued exemption after expiry needs a fresh approval, not continued possession of the old paper.5

Open-ended transfers outgrow posting relief​

Relief fits temporary postings with a home base to return to. An indefinite assignment belongs in the Japanese system after the cap, and planning should assume conversion rather than perpetual extension.5

See also​

References​

Footnotes​

  1. Japan Pension Service. Posting relief and Japan-side waiver after presentation of the Certificate of Coverage. https://www.nenkin.go.jp/international/english/ ↩ ↩2 ↩3 ↩4 ↩5 ↩6 ↩7 ↩8 ↩9 ↩10 ↩11 ↩12 ↩13 ↩14 ↩15

  2. US Social Security Administration. Certificate of Coverage request flow for Japan (Form SSA-2490 route and online request). https://www.ssa.gov/international/status.html ↩ ↩2 ↩3 ↩4

  3. US Social Security Administration. US-Japan posting relief up to 5 years (treaty text). https://www.ssa.gov/international/Agreement_Texts/japan.html ↩ ↩2

  4. UK Government. HMRC issue of posting documents for Japan assignments. https://www.gov.uk/national-insurance-if-you-go-abroad ↩ ↩2

  5. Japan Pension Service. Duration cap, extension in some treaty cases, and conversion to the Japanese system when the transfer exceeds the cap or is open-ended. https://www.nenkin.go.jp/international/english/ ↩ ↩2 ↩3 ↩4 ↩5 ↩6

  6. Japan Pension Service. Lump-sum withdrawal as the prospect when double contributions accrued without a certificate. https://www.nenkin.go.jp/international/english/ ↩ ↩2