The minimum age requirement for legal online sports betting varies depending on the state or the country. Generally, the minimum age is 18 years for online sports betting. However, if your state mandates that the legal sports betting age is 21, you must adhere to this rule. While a valid ID is not required for registration, it is necessary to verify your identity before withdrawing any winnings. Failure to comply with this requirement may result in forfeiture of your winnings.