You can only claim the deduction if the income is subject to Maryland tax- and if you are residents you are taxed by Maryland (even if you get a credit for taxes paid to a nonresident state).
Maryland provides a deduction for two-income married couples who file a joint income tax return. When both you and your spouse have taxable income, you may subtract up to $1,200 or the income of the spouse with the lower income, whichever is less.