In 2026, you generally do not need to submit an SG Arrival Card (SGAC) if you are only transiting through Singapore Changi Airport. The requirement applies strictly to travelers who intend to clear immigration and enter the country. If you are staying within the "transit area" (the sterile airside zone) to wait for your connecting flight and your bags are checked through to your final destination, you can bypass the SGAC entirely. However, if your transit involves a long layover and you wish to pass through immigration to visit the city, see the "Jewel" waterfall (which is outside the sterile area), or stay at a hotel outside the airport, you must submit the SG Arrival Card and the electronic health declaration within three days of your arrival. Additionally, if you are traveling on separate tickets and need to clear immigration to collect your luggage and re-check it for a different airline, you are technically "entering" Singapore and will need to complete the digital card. It is a free service provided by the Immigration & Checkpoints Authority (ICA) and can be completed quickly via their official website or the MyICA mobile app.