Filing separate tax returns may allow you to claim more deductions.
Filing a joint return saves taxes for a married couple where one spouse earns all, or substantially all, of the taxable income. If both you and your spouse earn taxable income, you should figure your tax on joint and separate returns to determine which method provides the lower tax.
Although your tax rate will generally be higher on a separate return, filing separately may provide an overall tax savings (for both of you together) where filing separately allows you to claim more deductions. On separate returns, larger amounts of medical expenses, casualty losses, or miscellaneous deductions may be deductible because lower adjusted gross income floors apply. Unless one spouse earns substantially more than the other, separate and joint tax rates are likely to be the same, regardless of the type of returns filed.
Suspicious of your spouse's tax reporting? If you suspect that your spouse is evading taxes and may be liable on a joint return, you may want to file a separate return. By filing separately, you avoid liability for unpaid taxes due on a joint return, plus interest and penalties.
If you do file jointly and the IRS tries to collect tax due on the joint return from you personally, you may be able to avoid liability under the innocent spouse rules. If you are no longer married to or are separated from the person with whom you jointly filed, you may be able to elect separate liability treatment.
Standard deduction restriction on separate returns. Keep in mind that if you and your spouse file separately, both must either itemize or claim the standard deduction. Thus, if your spouse itemizes deductions on Schedule A of Form 1040, your standard deduction is zero; you do not have the option of claiming the standard deduction and must itemize your deductions even if they are much less.
Switching From Separate to Joint Return. If you and your spouse file separate returns, you have three years from the due date (without extensions) to change to a joint return. If a joint return is filed, you may not change to separate returns once the due date has passed. The filing of separate or joint estimated tax installments does not commit you to a similar tax return.