"get some kind of pay back"
Although there are refundable credits (government handouts) for claiming qualified child dependents, there are no such credits for adult dependents. An adult dependent ( "Qualifying Relative" in IRS parlance ) only gets you a $4000 deduction from income before tax is calculated. In addition, there are restrictions are on claiming a spouse as an actual dependent . So, you get the same benefit (and more) by filing a joint return with your spouse. This is allowed. even if the spouse has 0 income.
