If you are married filing separately, you can take your spouses exemption only if your spouse is not filing a return, had no income, and was not the dependent of someone else. If your spouse meets these qualifications, you may claim the spouse's exemption.
If at the end of the taxable year, you were divorced or legally separated, you cannot take an exemption for your former spouse. If you were separated by a divorce that is not final (interlocutory decree), you may take an exemption for your spouse if you file a joint return.
If your spouse died during the taxable year and you did not remarry before the end of the taxable year, check the boxes for the exemptions you could have taken for your spouse on the date of death.