If your spouse refuses to sign a joint tax return, there isn’t much you can do without their consent. Provided your spouse is eligible to use an alternative filing status, the Internal Revenue Service will not force them to choose one status over another. As a result, you still have an obligation to file a separate tax return, but you can only use the married filing separately or head of household filing status.
TL;DR (Too Long; Didn't Read)
If your spouse refuses to sign a joint tax return, you'll be forced to complete a tax return under the married filing separately status.
Joint Return Consent
There are only two requirements to filing a joint return with your spouse. The first is that you be legally married by the end of the tax year, and the second is that you both consent to the joint filing. And since the only way the IRS can infer consent is when you and your spouse sign the bottom of a joint tax return, you aren’t eligible to file the return without two signatures.
Married taxpayers who choose not to file jointly will in most cases file as married filing separately. This requires that you only report the income that you earn separately from your spouse. However, if in prior years you file a joint return, you should evaluate whether you have an obligation to file one separately. The IRS requires married taxpayers who file separately to file a return when their gross income is equal to or greater than one personal exemption. For example, as of the time of publication, one personal exemption is equal to $4,050, so unless you earn at least $4,050 of income that isn’t tax exempt, it’s not necessary to file a separate tax return. At the same time, though, the standard deduction has doubled in 2018 to $24,000 for married couples who file jointly and $12,000 for those filing separately and the personal exemption has been done away with altogether.
The other option you have when not filing a joint return is to use the head of household filing status. However, this is only available if the IRS considers you unmarried despite the fact that you are legally married throughout the tax year. To qualify, you must maintain a separate household from your spouse during the last six months of the tax year. In addition, at least one child, stepchild or foster child who is eligible to be your dependent must reside with you for more than half the tax year and you must provide the financial resources for more than half the costs of maintaining that home.
Pros and Cons
The main benefit of filing a joint tax return with your spouse is the lower tax rates to which larger portions of your joint income are subject. However, you share in the liability for all tax debts, even in cases where only one spouse earns all of the income. Filing separately eliminates this joint liability but precludes one spouse from claiming a standard deduction when the other spouse itemizes, imposes less favorable tax rates on each spouse’s income and renders both spouses ineligible to claim many tax credits and deductions. But if you qualify to file as head of household, your separate income is subject to lower tax rates than married filing separately taxpayers and you are eligible for a larger standard deduction.