Qualifying for the Mortgage Interest Deduction. Mortgage interest includes that which you pay on loans to buy a home, on home equity lines of credit and on construction loans. The deduction is limited to interest paid on your main home and/or a second home. Interest paid on a third or fourth homes isn't deductible.
The statute of limitations on how far back the IRS can audit (called the Assessment Statute Expiration Date or ASED) varies depending upon the circumstances of the tax return. In most cases the IRS will not go back more than 3 years unless there is something very wrong with the tax return that was filed.
The time periods can be even longer than six years in some cases. The IRS has no time limit if you never file a return. For unfiled tax returns, criminal violations or fraud, though, the practical limit is usually six years. Another scary rule is that the IRS can audit forever if you omit certain tax forms. Plus, once an assessment is made, the IRS collection statute is typically 10 years. In some cases, the IRS can go back 30 years. In Beeler v. Commissioner, the Tax Court held Mr. Beeler responsible for 30 year-old payroll tax penalties.