General

• In general, a person must be a legal adult, which in the United States is defined as being at least 18 years old, in order to sign a contract. In cases where the purchase of an item or other circumstances requires a legal signature, the parents or guardians of a minor may sign a contract on the minor's behalf, agreeing that they will be responsible for making sure that the terms of the contract are upheld.
  
  

Exceptions

• Minors who are enrolled as full- or part-time students in a university or college may sign promissory notes, which are legally binding contracts between the borrower and the lender. Student loans are classified as necessary living expenses under the law.
  
  

Considerations

• Legal contracts that are signed by minors are considered to be unenforceable and invalid.