Facing increasing operational demands and already constrained by a lack of space, the Immigration and Checkpoints Authority (ICA) is looking to more than double the size of its Kallang Road headquarters.
It is proposing to erect a new building on the current site of an adjacent carpark by early 2021.
The ICA also wants to upgrade the current building and estimates that total works will cost $300 million.
Last Friday, the ICA called for a show of interest from firms "to render architectural consultancy" through a Request for Information (RFI) on government procurement website GeBIZ.
The RFI closes next Thursday.
The current ICA building has been around since 1997. The ICA, which was formed in April 2003, inherited the building.
"Over the years, ICA has continued to take on new initiatives and functions to augment operational capacity," it said.
"All available spaces have been exhausted and the present building can no longer sustain ICA's current and future operating needs. It is a less than ideal operating environment as the current space available has been saturated."
The site occupied by the current ICA building is approximately 0.8ha with a gross floor area of about 36,300 sq m. The land area ICA is considering for its new building is about 1.1ha and can achieve a floor area of around 46,200 sq m.
The documents state that the new ICA building will house service centres, a heritage centre, the Registrar of Societies and the Casino Regulatory Authority.
It will also "function as a convenient one-stop centre offering public services as well as provide enhanced capacity for the projected increase in workload".
The ICA told The Straits Times: "With the increased volume of customers over the years, more space will be required to cope with the demands for ICA services. This (RFI) is part of ICA's capacity and infrastructure planning for the long term, with the aim to serve our customers better."