7. Filing under the wrong status
The Internal Revenue Service applies different income tax rates and awards different standard deductions according to your filing status: single, married filing jointly, married filing separately, head of household or qualifying widow(er). For example, married couples filing jointly are actually entitled to twice the standard deduction of single filers.
Also, bear in mind that married partners who file separately are subject to different rules than those who file jointly. In other words, if you want to file separately, both spouses need to claim either the standard or itemized deductions but not one of each.
