Married taxpayers have the option of filing a joint return or each filing their own separate returns. Generally, filing jointly produces a lower aggregate tax, while filing separately may be advantageous to one spouse. Joint filers are jointly and severally liable for all income tax, related penalties and interest, including later determined deficiencies, subject to innocent spouse relief.
Only individuals who are married at the close of the tax year may file a joint return. Spouses legally separated under a decree of divorce or separate maintenance are not considered married for tax purposes. If a taxpayer is unmarried, he or she must file as a single taxpayer unless he or she meets the requirements for filing as head of household, which has lower marginal rates.