Does anyone know how many years back the IRS can go back for a personal and business audit? Is it 7 years, if memory serves me correctly?

The statute of limitations ("SOL&quot limits the time during which an action for assesment can be brought by the IRS.

The IRS has 3-years to audit a tax return and a 10-year SOL for the IRS collecting tax.
Under section 6501(a) of the Internal Revenue Code (IRC) and section 301.6501(a)-1(a), the IRS is required to assess tax within 3 years after the tax return was filed with the IRS. Similarly, under 301.6501(a)-1(b) no proceeding in court by the IRS without assessment for the collection of any tax can begin after the expiration of 3 years.

Under section 6501(e) of the IRC and section 301.6501(e)-1 the statute of limitations is 6 years if the taxpayer omits additional gross income in excess of 25% ("substantial understatement of income) of the amount of gross income stated in the tax return filed with the IRS.

If the tax return was prepared by the IRS under the authority of section 6020(b) of the IRC the statute of limitations does not apply. See section 6501(b)(3) of the IRC and section 301.6501(b)-1(c).

The SOL does not apply in the case of a false tax return or fraudulent tax return filed with the IRS with intent to evade any tax. See section 6501(c)(1) of the IRC and section 301.6501(c)-1.

For assessments of tax or levy made after November 5, 1990, the IRS cannot either collect or levy any tax 10 years after the date of assessment of tax or levy. See Section 6502(a)(1) of the IRC and section 301.6502-1. Court proceedings must also be started by the IRS within the 10 year SOL. Section 301.6502-1(a)(1).

For assessments of tax or levy made on or before November 5, 1990, the IRS cannot either collect or levy any tax 6 years after the date of assessment of tax or levy. See section 6501(e). However, if the 6 year period ends after November 5, 1990, the SOL is 10 years. In order to come under the 6 year statute of limitations, the 6 year period must end prior to November 5, 1990.

The 10 year SOL can be extended by agreement between the taxpayer and the IRS provided the agreement is made prior to the expiration of the 10 year period. See section 6501(c)(4) and section 301.6501(c)-1(d).

A taxpayer may file a claim for a tax refund of an overpayment of any tax within 3 years from the time the tax return was filed with the IRS or 2 years from the time the tax was paid to the IRS, whichever period is the last. If no tax return was filed with the IRS, the claim may be made within 2 years from the date that the tax was paid to the IRS. See section 6511(a).

Under section 6511(d)(1) a taxpayer may file a claim within 7 years if the tax refund pertains to a bad debt under section 166 or 832(c) or in connection with a loss from a worthless security under section 165(g).