You can never claim your spouse as a dependent on your taxes. This holds true regardless of whether they work or have taxable income from sources other than employment. However, you can, under some circumstances, claim an extra exemption for your spouse equal to what you claim for other dependents. Of course, you must meet the requirements set forth by the Internal Revenue Service, or IRS, before taking the exemption.
There are two kinds of dependents, qualifying children and qualifying relatives. A qualifying child must be your descendant, a younger sibling or a niece or nephew who lives with you and whom you support. A qualifying relative is someone you help support who is either a member of your household or a close relative living apart from you. The tests for claiming a dependent have many exceptions, considerations and special situations so you should check the IRS guidelines before you claim anyone.
A married couple filing a joint tax return can claim two exemptions, one for each spouse. If you file separately, you can claim an exemption for your spouse provided he received no gross income during the year and is not filing a return of his own. You can't claim an exemption if anyone else can claim your spouse as a dependent; it doesn't matter whether anyone does claim him, only that someone can. You can claim a second exemption on the same terms you're married but qualify to file as a head of household.
Normally, the IRS considers you married or single based on your status on the last day of the tax year. If your spouse dies during the year, however, you can file as a married person. If you are entitled to claim an exemption for your spouse while he lived, you can claim one for the year of his death. If you and your spouse divorce during the year, you cannot claim an exemption for him, even if you provided all his support during the marriage.
Qualifying Widow or Widower
You can file as a married individual the year your spouse dies, but no longer than that. If you qualify as a widow or widower with a dependent child, you can use that status for the following two years, as long as you don't remarry. You don't file a joint return, but you can claim the same standard deduction as a couple filing a joint return, double that of a single individual.