In credit card purchases, the maximum amount the merchant can charge to the buyer's card without getting authorization. For a charge above the floor limit, the merchant must obtain authorization from the card issuer. A zero floor limit means every credit card transaction has to be authorized. The floor limits usually come into effect where swiping the card is not possible for any reason and the transaction is not completed electronically. Otherwise, in all credit card transactions conducted over phone lines (by using a magnetic card reader), the merchants typically prefer to obtain electronic authorizations even for small amounts. In case of debit cards, all transactions have to be authorized. also called fallback limit (in the U.K.)