There are 5 filing status options on a tax return:
- Single
- Married Filing Jointly
- Married Filing Separately
- Head of Household
- Qualifying Widower

To determine how you should file, consider what your status was as of 12/31. Even if your status changed throughout the year, the IRS is asking about a tax payer’s status as of the last day of the year.
If you’re still not sure, talk to your CPA or give the IRS tool a shot: