An IRS tax form used by taxpayers to request relief from a tax liability involving a spouse or former spouse. Couples filing a joint tax return both become responsible for the tax obligation, called joint and several liability. If additional tax has to be paid because of income, deductions or credits from one spouse (or former spouse), the other partner will still be liable. The taxpayer seeking relief should file Form 8857 as soon as he or she becomes aware of a tax obligation that the other spouse (or former spouse) should be solely responsible for.
Getting a porce doesn't stop the IRS from considering both parties still joint and severally liable for a tax obligation, even if a porce decree states that only one party is responsible for the tax. A spouse or former spouse has two years to file Form 8857 from when the IRS first starts trying to collect for the obligation.