Beginning on September 1, 2018, the Singapore Corporate Access (CorpPass) will be the only mode to log in to Singapore Customs’ e-Services.
Singapore Customs advises users of e-Services to register before September 1, 2018.
The Singapore Customs notice may be found here:
https://www.customs.gov.sg/-/media/cus/files/notices/2018/notice152018-ver1.pdf
The CorpPass services may be found here:
https://www.corppass.gov.sg/corppass/common/aboutus