All Central Provident Fund (CPF) online services have been fully restored following "extensive testing and validation checks", the CPF Board said yesterday.
However, it advised users with non-urgent queries to log in after 10pm to ease traffic on its website.
"We continue to see a large number of log-ins to the e-services on our website, so members may encounter slow or intermittent access," the board said in a statement.
Following a website upgrade at the start of the month, some CPF online services, such as the checking of Giro application status, had become unavailable.
According to the board, this was because an "integration component" had malfunctioned due to high site traffic, causing the wrong information to be displayed.
On Monday, the entire system was taken offline as a safeguard while the board worked with its vendor, Microsoft, to progressively restore online services.
By Tuesday, most e-services were back online.
"We will closely monitor the performance of the e-services system and make improvements as necessary to enhance members' experience," said the board.
On Tuesday evening, the CPF Board also warned members of a duplicate of its site.
The fake site has since been taken down.
Members of the public were encouraged to stay alert for such phishing sites, which try to trick people into entering personal data.