noun
omission in a bill; missing item on a check
Refers to an item or charge that was accidentally left off a bill or account, especially in restaurants or shops.
会計のとき、付け落ちがないか確認してください。
When paying, please check that nothing has been left off the bill.
この伝票には付け落ちがあるようです。
It seems there is an omission on this slip.
Compound of 付け (つけ, 'bill' or 'account') and 落ち (おち, 'omission' or 'drop'), from the verb 落ちる (to fall/drop).