Can staff bill an item that shows zero stock?
By default no: the counter says “Insufficient stock: … available, … requested”.
For sell-first-enter-later days, switch on “Allow billing into negative stock” in Settings → Counter & policies → At the counter. Every such bill shows in the stock report.
WhereSettings → Counter & policies in the back office
Also asked as
- “negative stock billing”
- “Insufficient stock error at the counter”