I believe at 14 years old. give them a part time job allow them a small limit of $200.00 and let them use 51% of the credit line available say $102.00 and let them make above the monthly payment of about 5 dollars until it is paid off and then let them see what it does to the credit report. It is simple math. Lots of adults go into this world today without the knowledge of balancing a check book let alone credit scores (that are extremly simple). treat your child like a choild and a child is what you will have. treat them with respect and allow the to be responsible and see what happens. let them watch their credit report online so they can see what a company is talking about when they mention identity theft.