In order to request any innocent spouse relief, you must prepare and file IRS Form 8857 (Request for Innocent Spouse Relief). In addition to filing this IRS form, you must also include a statement explaining why you qualify.
IRS Publication 971 (Innocent Spouse Relief) contains information which can help you.
If you do not make the election for innocent spouse relief within two years from the date the IRS first began collection activities against your joint return, you will forfeit any chance to receive it. Be certain, therefore, that you fill out and mail Form 8857 as soon as possible.
You can obtain IRS Form 8857 via the IRS website (by printing or downloading), ordering online; by phone, or by mail.