Even though you file jointly now, only your wife is responsible for the tax debt that she incurred before you were married. That's why the letter is addressed only to her.
Certain events can extend the 10-year collection deadline. See the following on the Taxpayer Advocate Service web site.
Collection Statute Expiration Date (CSED)
TAS Tax Tip: Understanding your Collection Statute Expiration Date (CSED) and the time the IRS can c...
If none of the listed events apply to your wife, she should first call the IRS and ask what their records show as her CSED. If your tax return was filed after the CSED, see if the letter has instructions for what to do if she disagrees with it. If the CSED has been extended, she will have to look into why it was extended. She might need help from a tax professional who has experience with IRS collections.
Since only your wife is responsible for the debt, you can recover your share of the refund from your joint return by filing an injured spouse claim, Form 8379. But if the CSED has passed and the IRS should not have collected the debt, you and your wife should direct your efforts to recovering the full refund, instead of just your part of it.
Form 8379
Instructions for Form 8379
You have a difficult situation, and IRS rules and procedures can be confusing and hard to understand. If you cannot resolve the problem easily, you should get professional help.
