Back in 2008, Ms Jean Tan, Director, Corporate Communications for Permanent Secretary Ministry of Manpower, made this remark on Rules on Off-In-Lieu:
For an employee on a five-day work week, Saturday would be considered a day-off and Sunday a rest day.
Under the Employment Act, if a public holiday falls on a day-off, an employee is entitled to one day off-in-lieu or be given one extra day's pay.
If it falls on a rest day, the law provides that the working day following the rest day will be a paid public holiday.
A more recent article on this topic was published on the Manpower Ministry website and I quote:
For employees who are not required to work on Saturdays, they are entitled to claim a day off or compensation in lieu for that public holiday if they are covered under the Employment Act. It is therefore not up to the employer’s discretion or goodwill to grant their employees a day off in lieu under the law.