on the slate
on the slateBRITISH, OLD-FASHIONED
If you buy something on the slate, you have it now but promise to pay for it later. Note: In the past, people used pieces of a dark grey stone called `slate' for writing on, for example in schools, shops, and pubs. Shopkeepers and pub owners would write customers' debts on their slates, and wipe them clean when the debts were paid. If a man was unemployed at the time, some kindly shopkeepers would put it `on the slate' until the next payment came.
on the (or your) slateto be paid for later; on credit. British
Shops and bars formerly kept a record of what a customer owed by chalking it on a tablet made of slate.
(put something) on the ˈslate(informal) (put something) on your account in a shop, a bar, etc. to be paid for later: Can I put this on the slate?
A slate is a thin sheet of a type of dark grey stone that was used in the past to write on.