Credit Cards & Debit Cards
Credit cards issued by or affiliated with a US bank (or any other US financial institution) are not accepted in Cuba.
Most cards with a VISA or MASTERCARD logo and non US affiliated.
Some example of useless cards:
American Express, MBNA, City Bank, Capital one, Diners, Egg, Marks & Spenser, Maestro, Alliance & Leicester, any MasterCard from a Canadian Credit Union, or any other credit card with US affiliation.
Check with your bank to make sure that your credit card will be accepted in Cuba. And before traveling to Cuba, you should always call the issuer of your credit card to notify them of your travel plans (where and for how long); as you should always do if you're traveling abroad.
Credit cards are accepted as a form of payment in most hotels and resorts, big restaurants, large stores, and travel and tours agencies; but usually not in open-air markets, handicraft kiosks, small restaurants, casa particular (B&B), smaller hotels or hotels outside the popular tourist areas, privately own restaurant (paladar), street vendors, and many other places off the beaten path.
Credit cards can also be used in banks or cadedas to get a Cash Advance, but remember that your credit card company will charge interest starting the day of the transaction.
Given that the CUC (Cuban Convertible Peso) is not traded internationally, all transaction on credit cards are charged in $USD (remember that 1 CUC=1 USD), and an administration fee of 3% is added to each transaction. For example: if you buy something which costs 100 CUC you credit card will be charged $103 USD, and then you credit card company will convert the amount to your local currency.
DEBIT CARDS & ATM (aka ABM)
Debit cards have been ineffective in Cuba for a long time, but it's slowly starting to change. Now only the debit cards with a Visa or MasterCard logo on them works, but in an ATM (Automated Teller Machine) only the one with a Visa logo works, for a MasterCard debit card you have to go inside the bank and see a teller. The biggest problem remain to actually find an ATM, and one which is working! They can be found in larger cities and some major tourist areas. In Varadero there’s one in the Plaza America. In retail Direct Payment (interac) with a debit card is not available anywhere in Cuba.