If a minor makes such a contract it can be reneged without penalty.  In Iowa a minor can only be bound to contracts for necessities like apartment, clothing, food, etc.  However if such a contract was made and the minor kept, for example a car, past their 18th birthday then they would be liable under the terms of the contract.  If it is a contract for a necessity then the terms of the contract must be fair.  For example if a minor gets an apartment for $450 when similar apartments in the building are rented to other tenants for $400 then the minor will be liable for the contract but only for $400.