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.
How far back can the IRS go? How far back in time can the IRS audit? Three Year Rule The period or Statute of Limitations at the Federal level which allows them to audit you without cause, begins on the date that you file your federal return and extends 36 months or three years.