What causes tingling on heel of feet?

This can be. an entrapped nerve. Sometimes referred to as tarsal tunnel syndrome or a basters nerve entrapment. If its on both feet it may be due to a systemic disease like diabetes. There are many causes, I am just mentioning common ones here.
Possible neuropathy. Depending on the affected nerves, symptoms of diabetic neuropathy can range from a numbness and tingling sensation, possibly a burning sensation, to an uncomfortable painful sensation of the extremities. Neuropathy may affect your digestive system, urinary tract, blood vessels and the heart. For some people, the symptoms are mild; for others, it can be painful and disabling.