Depending on where you live, there are often state laws and local ordinances that may impact how much work you have to go through in order to become a private investigator. About a dozen states require PIs to hold a state license, but most states do not. In some states you may be able to carry a gun, and in others you may have to get a special license to carry. Check here for a complete list.

Cities may require you to get a business license or file an assumed name certificate (which you should do, anyway, to protect whatever name you choose for your business)..

Generally, no formal education requirements exist for most private investigator jobs, although most private detectives have at least a high school diploma. A growing number have college degrees, and many have even taken law courses or formal courses in criminal investigations. Few have advanced degrees or education, including such specialities as Certified Fraud Examiner, or Certified Document Examiner.

Work experience is probably the most common qualification, however. Private detectives and investigators tend to have prior experience in other occupations. Many have experience working for insurance or collection companies, others have experience in the private security industry, while most tend to be former police officers or federal agents. An increasing number have experience working as paralegals.

To be a successful PI, it generally helps to have a good background and working knowledge of the law, both civil and criminal, bearing in mind that many investigators enter the field after working in reguar law enforcement, the military, government auditing and investigative positions, or federal intelligence jobs.