If you are working and your spouse is staying at home, or vice versa, the SAHS could qualify as a dependent member of your household, and you could take an exemption for her. To qualify, she must:
- Have earned less than $3,800 in gross income or unemployment benefits for the year 2012
- Have received more than half of her support from you, in the form of food, clothing, shelter, education, medical and dental care, recreation, and transportation
- Be a U.S. resident or citizen, or a resident of Mexico or Canada
For more on exemptions and how they work, read this.
If your spouse qualifies as a dependent, that also means you could qualify to claim education credits if you are paying for her education. To find out more, read this.