If you're holding pre-2019 Singapore dollar notes, they're no longer legal tender. The Monetary Authority of Singapore (MAS) demonetized all "Portrait Series" (1999–2019) and earlier designs effective January 1, 2021.
Current legal tender: Only the "Portrait Series" polymer notes (issued 2019 onward) and the "Bicentennial" $20 commemorative (2019). Paper notes—including the widely circulated $2, $5, $10, $50, $100, $1,000, and $10,000 denominations—cannot be used for transactions.
What to do with old notes:
Coins are unaffected—all Singapore coins remain legal tender regardless of issue date.
For travelers: Don't accept old paper notes in change. Vendors sometimes offload them on tourists. If stuck with them, airport banks (Changi) can exchange before departure.
Verify current policy at mas.gov.sg—MAS occasionally updates exchange procedures.