The IRS looks for nonfilers through its computerized Information Returns Program (IRP). This tremendously effective operation matches information documents, such as W-2s and 1099s form payers against the tax returns you have filed. If the computer search fails to find a return, the IRS initiates a taxpayer Delinquency Investigation, or a TDI. A TDI is an IRS search for a taxpayer to discover why he or she did not file a tax return. TDS’ usually begin with computer generated notices. If you don’t respond to the notices, your case is normally turned over to a Taxpayer Service Representative for a telephone contact or more letters. Failure to respond will lead to a contact to A Revenue Officer at your local IRS office. This means that the IRS is serious and you should contact a professional immediately.