If you're married and file a separate return, you'll usually pay more tax than if you use another filing status that you qualify for.
Also, if you file a separate return, you can't take the student loan interest deduction, the qualified tips deduction, the qualified overtime compensation deduction, the enhanced deduction for seniors, or the education credits, and you'll only be able to take the
Earned Income Credit and
Child Care Credit in very limited circumstances. You also can't take the
Standard Deduction if your spouse itemizes deductions.
It's rare for
Married Filing Separately to give you more refund than
Married Filing Jointly. However, if you itemize your deductions and one spouse has a large amount of medical expenses or casualty losses, you may get more overall refund by filing separate returns.
When someone chooses to file a separate return, it is usually because of reasons other than getting the largest refund, such as if one spouse may be cheating on their taxes and the other spouse doesn't want to be responsible for any tax problems the other spouse will have if he or she is audited.
The following IRS tool can help you determine what filing status to use:
What Is My Filing Status