Filing status is a category the IRS uses to determine your tax rates and which standard deduction you qualify for. There are five statuses: Single, Married Filing Jointly, Married Filing Separately, Head of Household, and Qualifying Surviving Spouse. Your status on December 31 determines your status for the whole year. Choosing the right status can significantly lower your tax bill. If you're unsure which applies, the IRS has a free tool to help you figure it out.