There are numerous ways a business gets selected for an audit. The most common are referral from another division of the Department of Revenue, referral from another City Department, information obtained during another audit, referral from another business, referral from the Illinois Department of Revenue or random selection from registered taxpayers within each tax.
Many variables affect the time required to complete an audit.
Generally, a taxpayer can expect an audit to extend over a three to four-month period with the auditor spending approximately three to four weeks at the audit site in total.