Briefly, single is the basic filing status for unmarried people who do not qualify to file as Head of Household. If you were not married on the last day of the tax year and you do not qualify to use any other filing status, then you must file your tax return as Single. See the tax rates for Single filers.
To see if you qualify as a Single filer, you must ask yourself 2 questions:
- Was I married on the last day of the year?
- Do I qualify for any other filing status?
1. If you answered "Yes" to the first question (you were married on December 31), then you cannot file as Single unless you were legally separated. If you were married and not legally separated on December 31, you will need to use one of the married filing statuses (Married Filing Jointly or Married Filing Separately).
2. If you answered "Yes" to the second question (you do qualify for another filing status), then you can file as Single, but you may get a bigger tax refund (or owe less taxes) if you use another filing status on your tax return.
For more information, refer to https://wwww.irs.gov or https://www.efile.com/single-tax-filing-status/