When it comes to your filing status for tax purposes, only one day of the year matters: December 31. If you were still legally married on the last day of the year, you typically cannot file your taxes as a single taxpayer, even if you were no longer living with your spouse. It's never that simple with the Internal Revenue Service, however, and some exceptions exist.
Single status depends on the nature of your marital separation. If you're legally separated – and not all states recognize this concept – you can file as a single taxpayer even if you're not divorced by December 31. In this case, the IRS accepts your decree of separation as sufficient proof that your marriage has ended. You need a decree or judgment to qualify for this loophole, however. A separation agreement isn't enough, and if you and your spouse have simply relocated to separate households, the IRS says you're still married and you can't file a single return.
Head of Household
If you don't have to file as a single taxpayer, you may not want to. It's usually more beneficial to file as head of household if you qualify – and you can potentially qualify even if you and your spouse are just living separately without a decree or judgment. The catch is that you can't have lived together the last six months of the year, and some other rules apply as well. You must have paid more than half your household's expenses and you must have a dependent for whom you can claim an exemption. As long you and your spouse don't live together past June 30 and you meet all other criteria, your legal marital status doesn't affect this filing option.
Married Filing Separately
If your divorce isn't final by December 31, if you don't qualify as head of household, and if you don't have a decree legally separating you, you have no choice but to file as a married taxpayer. This leaves you two options: filing separately or filing a joint return. Filing separately has a few disadvantages. You need only report your own income, but you lose out on certain tax benefits such as education-related tax credits and the child and dependent care credit. The tax brackets for determining the portion of your income that you must pay in taxes are set much lower for separate filers than those for couples who file jointly.
Married Filing Jointly
Assuming you and your spouse maintain a civil relationship, you can still file a joint return together if you want to and if you don't have a traditional divorce decree or a decree of legal separation before year's end. This allows you to take advantage of the tax benefits you'd be excluded from if you filed separately. If you do so, however, you may not be able to change your mind later. You can’t amend your return to separate married status past the tax deadline, usually April 15.
Beverly Bird has been writing professionally for over 30 years. She specializes in personal finance and w, bankruptcy, and she writes as the tax expert for The Balance.