Innocent spouse relief

Your premise is correct:  that you can file a special tax form in an attempt to prevent your portion of a joint income tax refund from going to pay alimony (or any other debts) owed by your husband.

However, we need to be sure to get the terminology right here (as it is important in your case).  There actually exists a tax form, and a related procedure, called "Innocent Spouse" relief.  But there is also a tax form, and procedure, called "Injured Spouse" relief.

Although it can be very easy to get the two confused, because of the similar-sounding name, they are not actually the same thing, and they do require different tax forms and processes.  You can read about those differences between Innocent Spouse and Injured Spouse at the following TurboTax Frequently Asked Questions (FAQ) webpage:

https://ttlc.intuit.com/questions/1901549-what-is-an-innocent-spouse-and-how-does-it-differ-from-an-injured-spouse

That said, and in direct reply to your original question, what you will actually want to request from the IRS is known as Injured Spouse relief.  You can read about this tax form, as well as the instructions on how to mechanically begin to complete one in TurboTax, at this internet link:

https://ttlc.intuit.com/questions/1910698-how-do-i-file-form-8379-injured-spouse-allocation

You may additionally be interesting in reading what the IRS itself has to say about Injured Spouse applications at the following IRS.gov website:

https://www.irs.gov/uac/seven-facts-about-injured-spouse-relief


Thank you for asking this important question.