How many audit working papers are normally selected for QA sample purpose?

There is not a specific number required when sampling work papers. The IIA uses a 10-20% of audits rule of thumb in a quality assessment (QA) with independent team reviews taking into consideration the size of the IA Functionand the number of audits conducted per year. At a minimum, the independent QA  team should review at least two to three sets of working papers from the last four to six months. When conducting Self-Assessment with Independent Validation (SAIV), the norm is to review two-three sets of working papers that were reviewed as part of the self-assessment, and then to review a couple that were not reviewed as part of the self-assessment.