The shortfall of $1 billion comes as fare revenues fall far below the cost of government contracts awarded to transport firms.
The Land Transport Authority has awarded tenders to three firms for 60 electric buses, in its latest move to introduce more green vehicles for public transport.
Singapore's largest bus operator, SBS Transit, beat five other bidders in a competitive tender called by the Land Transport Authority in April 2017.
The Land Transport Authority called a tender for the third Government bus contract - called the Seletar package - to run 26 bus routes.
Eight of the 10 bidders vying for the second government bus contract have been shortlisted by the Land Transport Authority (LTA).
A South Korean group has set its eyes on the second Government public bus contract and has teamed up with a local firm to bid for it.
A second tender to operate bus services under the government contracting model was called by the Land Transport Authority yesterday.
The first public bus contract by the Land Transport Authority (LTA) has drawn a total of 11 bidders and the winner will be announced in April.
More than 20 firms are expected to submit bids for the first public bus contract, and most of these firms are foreign.
The Public Transport Tripartite Committee - headed by Minister Josephine Teo - announced three key recommendations for the bus industry yesterday.
The Public Transport Tripartite Committee outlined steps to safeguard the job security of bus drivers in the new contracting model.
Transport Minister has explained that regular fare increases are essential to keep the the new contracting model working and financially sustainable.