Three Types of Relief
Classic relief for understatements caused by the other spouse. Separation of liability for divorced or separated spouses. Equitable relief when the other two do not apply but holding you liable would be unfair.
Common Scenarios
Your spouse underreported business income. Your spouse had unreported side income. Your signature was forged. You signed under coercion. Each scenario has a path to relief through Form 8857.
The law recognizes that signing a joint return does not make you responsible for your spouse's mistakes.