(MONEY Magazine) – Sign a receipt or punch in a PIN? When it comes to debit cards, this seemingly banal decision at the checkout is a big deal for retailers. So much so that soon you may have less choice. On Feb. 1 you'll no longer be able to pay with a signature-based debit MasterCard at Wal-Mart. Merchants, led by Wal-Mart, have been in a slugfest with Visa and MasterCard for seven years. At issue: the fee merchants pay for signature-based debit (about 1.5% of the purchase) vs. PIN-based debit (about 15¢). As part of last April's settlement, Visa and MasterCard will let merchants negotiate lower fees and drop their debit cards even if they accept credit cards. So far, Wal-Mart is the only merchant to kick out a card, but "several major retailers are exploring their options with Visa and MasterCard," says Craig Shearman of the National Retail Federation. --MEGAN JOHNSTON