By which date does a taxpayer need to obtain a final divorce decree to be considered unmarried for the whole year?

To be considered unmarried for the entire tax year when filing taxes, a taxpayer must obtain a final divorce decree by December 31 of that tax year. This is essential because the IRS determines a taxpayer's marital status for the year based on their status at the end of the year. Therefore, having a finalized divorce by December 31 means that the taxpayer can file as single for that entire tax year.

Obtaining the final divorce decree before this date ensures that any obligations or benefits tied to filing status reflect accurate marital status. This rule applies irrespective of when the divorce proceedings commenced or whether the taxpayer was separated but not yet legally divorced by the start of the year. In summary, to accurately reflect one's status as unmarried for the whole year on their tax return, the critical date is December 31 of that tax year.