If you owe money for prior years and have a refund, the IRS will most likely apply your refund to the back taxes automatically.
However, the IRS does make mistakes. If you have not yet done so, it would be a good idea to carefully review your notice and 2014 return to make sure that the additional taxes they have assessed are legitimately owed.
If you used TurboTax to prepare your 2014 income tax returns, you may be covered by the TurboTax Audit Support Guarantee. You may be able to get assistance with the notice, also.
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