@Hal_Al wrote:
So, it comes down to the support test. If the amount of support your provided in the 5+ months you had them was more than the support provided by others, including payments by government agencies, you can claim them as a standard (not QC) dependent. Admittedly, it will be hard to come up with numbers for the first half+ of the year.
The IRS has a worksheet that can be used to help with the support calculation. See: http://apps.irs.gov/app/vita/content/globalmedia/teacher/worksheet_for_determining_support_4012.pdf The support value of a home is the fair market rental value, divided by the number of occupants. Admittedly, it will be hard to come up with numbers for the first half+ of the year.
The Other dependent (qualifying relative) credit is worth (up to) $500 per dependent and is non-refundable. That is, it can only be used to reduce an actual tax liability. No Child tax credit, no EIC.
If you did not provide more than half their total support, you can still claim them as "qualifying relative" dependents if you get a signed multiple support agreement letter from everyone who provided more than 10% of their support, agreeing that you can claim them.
This, of course, might be a big problem. But it might also be an opportunity for negotiation. You say "kids" (more than one). The biological mom also can't claim them as dependents because they did not live with her more than half the year. But if you were to offer to sign a multiple support agreement allowing you to claim child #1 and mom to claim child #2, then you both get something, instead of both getting nothing.
