When a married couple file separate returns, they can later amend and file a joint return. When they initially file a joint return, they cannot then file separate returns. However, under certain circumstances, one party may be able to separate the liability.
Innocent Spouse Relief allows individuals to be free of the debt of their spouse. Most cases involve an audit of a joint tax return where one party did not know or had no reason to know that there was an understatement of income or an overstatement of expenses. One factor that the IRS looks at is whether the requesting spouse benefited from the income. The easier cases involve a divorced or separated couple.
Every case is different and every fact is important. Not everyone qualifies as an Innocent Spouse, but those that do can save thousands of dollars and can put the tax burden on the responsible party.