Announcement of Changes to the Server Certificate and Security Settings of the Corporate Number Publication Site (Scheduled for Late October)

May 20,2026
National Tax Agency, Japan

Regarding the National Tax Agency Corporate Number Publication Site (hereinafter referred to as the "Publication Site"), it is scheduled that, in late October 2026, the certification authority issuing the server certificate will be changed to Amazon Trust Services ("ATS").

　In addition, as part of security enhancements, the security settings will be changed to use only more secure encryption methods among those compliant with TLS 1.2.

　Details such as the exact date and time of the configuration changes will be announced once they are finalized.

<Notes>
(1) Server Certificate
- Due to the configuration changes, the certification authority of the server certificate used by the Publication Site will be changed to Amazon Trust Services (ATS).
- Users may not be able to access the Publication Site if the root certificate used by ATS is not trusted by their operating systems or browsers.
- This root certificate is normally distributed automatically to major operating systems and browsers and is trusted. Please ensure that your operating systems and browsers are updated to the latest versions.
- For information on Amazon Trust Services, please refer to the official Amazon Trust Services website (external site).
(2) Encryption Methods
- Due to the changes in encryption methods, users may not be able to access the Publication Site from environments using operating systems approaching end of support or older communication protocols.