What is the required training to be an internal auditor?

ISO 9001 does not have required training only indicating that auditors must ensure objectivity and impartiality and cannot audit their own work.  What this means for each company may differ.  To ensure an effective program, auditors need to be able to interpret the meaning the clauses in the standard, review the ISO 9001 or TL 9000 processes, as well as associated supporting procedures.  You must be able to demonstrate the auditors are qualified through education, skills, and experience. You will also need to be able to show that you are asking thorough questions in order to conduct a comprehensive audit. Training on these procedures, auditing techniques and documenting results is critical to a long term successful QMS.