For the most part, if you don't have compensation income, such as wages, self-employment income or alimony, you can't contribute to an individual retirement account. However, the Internal Revenue Code has a special exception that allows non-working spouses to contribute to an IRA if they meet the spousal IRA contribution requirements. Of course, whoever is making the contributions still must meet the requirements to contribute to an IRA.
Married Filing Jointly
You must be married and you and your spouse must file a joint return. Spouses who do not file a joint return are ineligible to take advantage of a spousal IRA contribution. As of 2012, same-sex couples are not considered married under federal tax law, and therefore cannot file a joint return to take advantage of the spousal IRA contributions.
The working spouse must have compensation left over after his IRA contributions for the non-working spouse to be eligible to contribute to her IRA. The non-working spouse cannot contribute more than the smaller of the annual limit or the working spouse's compensation minus the working spouse's IRA contributions. For example, say the annual contribution limit is $6,000 and the working spouse has $10,000 in compensation. If the working spouse puts in the full $6,000 to his IRA, that only leaves a maximum $4,000 IRA contribution for the non-working spouse.
Standard Traditional IRA Requirements
Traditional IRAs also require that you be under age 70 1/2 at the end of the year for which you're making the contribution. In addition, just because you can contribute doesn't mean you can claim a deduction. If either spouse participates in an employer-sponsored plan and your modified adjusted gross income exceeds the annual limits, the contribution is allowed, but it's nondeductible.
Standard Roth IRA Requirements
Roth IRAs don't impose an age limit but do restrict your ability to contribute at all if your modified adjusted gross income is too high for your filing status. These limits vary from year to year with inflation and you can find the updated limits in IRS Publication 590. However, you don't have to worry about figuring the deductible portion -- all Roth IRA contributions are nondeductible.