The E-3 visa is a United States visa for which only citizens of Australia are eligible. The E-3 visa is similar in many respects to the H-1B visa. Important differences include the fact that spouses of E-3 visa holders may work in the United States without restrictions (unlike other U.S. non-immigrant visas, even the TN visa issued to Canadian and Mexican citizens), and that the E-3 visa is renewable indefinitely (in two year increments). There is an annual quota of 10,500 E-3 visas. Visas issued to spouses and children are not included in the E-3 quota and spouses and children do not need to be Australian citizens.