Under Ohio law, adults and minors (anyone under 18 years old) are treated differently when it comes to enforcing contracts for goods or services. WORKING PERMITS: Every minor 14 through 17 years of age must have a working permit unless otherwise stated in Chapter 4109.Consult with an experienced contract lawyer in your area to see if your contract is voidable immediately due to a minor's involvement. Minors are not permitted to enter a contract under certain exceptions such as sports contracts or purchase of goods. A minor under age 18 does not have full power to contract. Such persons are incompetent to enter into a binding contract. Learn about minors and contract law, including their rights, exceptions, and protections. Do not sign a contract until you are sure you understand it. Cross out or fill in any blank spaces on a contract before you sign it. Under Ohio law, minors (under 18) are not legally capable of signing contracts.