Generally, you must be at least 14 years old to have a job. However, there are a few exceptions in the law that will allow someone under the age of 14 to have a job.  

If your parent(s) owns a business, you can work there at any age. 

If you are at least 12 years old, you can work on a farm when school is not in session (summer vacation) if you parents give you written permission. 

Also, children under the age of 14 can work in show business (acting, singing, etc...).