Costco accepts a variety of payment methods, including Visa credit cards, Mastercard, Discover cards, and all Visa-branded debit cards. Costco also accepts mobile wallets like Google Pay, Apple Pay, and Samsung Pay, as well as cash, checks, and EBT cards for in-store purchases. However, Costco does not accept Mastercard, Discover, or American Express cards at warehouse locations. Additionally, Costco gift cards can be used as a workaround for using other credit cards for purchases. Its important to note that while Costco accepts most U.S.-based debit cards, it does not accept debit cards from American Express.