<prompt> Human: I have a two year old son with my Fiance. Last year I claimed him since I worked more but this year my fiance and I worked about the same amount. The question is can both of us claim him or since I claimed him last year shoulddo I claim him again? We split all costs other than insurance so we are contributing about the same amount.  <response>: If your son lived with both of you more than half the year, either of you can claim him. It doesnt matter who provided how much support: the support test for qualifying child dependent is simply that the child did not provide more than half his support.If you both try to claim him, IRS would apply tiebreaker rules.If the parents dont file a joint return together but both parents claim the child as a qualifying child, the IRS will treat the child as the qualifying child of the parent with whom the child lived for the longer period of time during the year. If the child lived with each parent for the same amount of time, the IRS will treat the child as the qualifying child of the parent who had the higher adjusted gross income AGI for the year.Source: Publication 17, chapter 3, section on Qualifying Child of More Than One Person 