Costco accepts several payment methods, including Visa-branded credit cards, the Costco Anywhere Visa Card by Citi, most PIN-based debit/ATM cards, Costco Shop Cards, cash, personal checks from current Costco members, business checks from current Costco business members, travelers checks, EBT cards, and mobile payment methods such as Apple Pay, Google Pay, and Samsung Pay. However, Costco does not accept American Express, Discover, or Mastercard credit cards in its warehouses. It is important to note that Costco members are allowed to purchase Costco Shop Cards online with a Mastercard, Discover, or Diners Club card, which can then be used at the warehouses. Additionally, Costco accepts Visa, Mastercard, and Discover credit cards for online purchases made on Costco.com.