However, it specifies that you can only get it when leaving from an airport (Changi Airport or Seletar Airport) or from a harbour (HarbourFront or Marina Bay Cruise Centre Singapore at Marina South).
The problem is that I am leaving by bus to Malaysia.
After reading more carefully, I saw that the process seems to be straight forward in Changi Airport because you can do it all using a machine, & this machine is located in the check-in hall.
So I'm wondering: can I simply turn up at Changi Airport & do the refund process, then just leave the airport?
I quoted the relevant text below, the only risky part seem the one where
Customs Inspection counter, where customs officers may ask to see your purchases for further verification. At that point, if they ask for a plane ticket, I'm worried they will not be amused when I show them a bus ticket to Malaysia instead.
Relevant parts of the web page
Collecting eTRS tickets when purchasing goods:
If you don’t have a credit/debit card, or don’t wish to use your card as a Token, you must remember to collect an eTRS Ticket from the retailer when you make a purchase. When you apply for your refund at the airport or cruise terminal, go to an eTRS self-help kiosk and scan all your eTRS Tickets one by one. You can then claim your refund by following the instructions on the kiosk.
Location of the eTRS kiosk:
If you are leaving by air, apply for your GST refund using the Electronic Tourist Refund self-help kiosks (eTRS kiosks) found at Changi Airport Departure Check-in Hall (before departure immigration)
Process at the eTRS kiosk:
At The eTRS Self-Help Kiosk: At the kiosk, swipe your passport and the credit/debit card that you have chosen as your eTRS Token. This will call up details of all your purchases. Alternatively, scan your eTRS Tickets individually to retrieve your purchase details.
After you have called up your purchase details, follow the instructions on the eTRS kiosk to apply for your GST refund. At this stage, you will be asked to choose whether you want your refund to be made to your credit card or in cash (for tourists departing from Changi Airport)
When you are done, the kiosk will issue you a Notification Slip. Read it to see whether you need to go to the Customs Inspection counter, where customs officers may ask to see your purchases for further verification.
Get the actual money back:
Collect Your Refund: If you are departing from Changi Airport, you can choose to receive your refund in cash, or have it credited to your credit card.
If you choose to have the refund credited to your credit card, you may proceed to boarding after completing your claims at the eTRS kiosk. The money will be credited to your specified credit card within 10 days.