Costco has a generous return policy, allowing customers to return any item at any time, regardless of any reason. However, exceptions include electronics bought at Costco within 90 days, diamonds that are larger than 1.00ct or larger, and items with a limited life expectancy such as tires and batteries sold with a product-specific limited warranty. Costco's general rule is that it does not accept returns on alcohol where prohibited by law, but can issue a refund if the situation warrants it. Despite this, there have been many Reddit threads pondering whether returns are permissible for alcohol.