A draft F5 every quarter
Each invoice at MAS's published rate for its date, and a plain list of anything in the way. You file in myTax.
A few questions a week
Each Monday it picks out bank lines whose account or GST code looks wrong, and asks about facts you know.
Read-only
It never changes your books and never files. Every question comes from rules you can see.
Keep me posted
Running on one Singapore company's books today. We'll tell you when there's room.