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.
Audit Time Limitation. Most taxpayers who file a complete and accurate tax return before the filing deadline can be audited by the IRS within three years of the filing deadline. For example, even if you file your tax return before the April 15 deadline, the three-year period doesn't begin until April 15.n the unlikely event you are chosen for an audit and the IRS increases the amount of tax you owe, you may be responsible for interest and penalties on that amount. For example, if the increase in tax is due to a negligent mistake you make, then the IRS will charge you 5 percent of the underpayment as a penalty.