The IRS initiates most contacts through regular mail delivered by the United States Postal Service. However, there are special circumstances when the IRS will call or come to a home or business. These visits include times when a taxpayer has an overdue tax bill, a delinquent tax return or a delinquent employment tax payment, or the IRS needs to tour a business as part of a civil investigation (such as an audit or collection case) or during criminal investigation.