When a taxpayer files an income tax return with a spouse
he or she assumes what is known as “joint and several
liability” with his or her partner. There is no division of the
liability between the signing parties, each is entirely
responsible for any tax liability, and for any information or
misinformation of a tax return which gives rise to a tax
liability including any additional tax liability that the IRS
determines to be due.

Simply expressed, if you are married and file a joint tax return both taxpayer
and spouse take full responsibility for the contents, including income reporting,
deductible expenses, and tax liabilities. There are situations where one spouse
believes that he or she did not know and should not be liable for jointly filed
tax return misstatements.

There is an IRS Form 8857, Request for Innocent Spouse
Relief, which the IRS says “You should file Form 8857 as
soon as you become aware of a tax liability for which you
believe only your spouse or former spouse should be
held responsible”. This is a complex form, consisting of
23 questions.