Only the "custodial parent" is allowed to take the child and dependent care credit, there are no exceptions. The custodial parent is defined by the IRS as the person with whom the child lived for the longer part of the year. 2007 had 365 days---your child had to have been with one of you for more days than the other. It would only be fair if you paid your exwife (and let her pay the day care provider) the child care costs and she uses the total costs paid to claim the credit and then splits the credit with you. However, there is no law that requires this. If your divorce decree or custodial agreement does not address dependency and or day care credit issues, then I urge you to apply for a modification of either your divorce decree or child support amount or both to address these issues. One suggestion would be to ask the court to order your exwife to pay a percentage of your day care costs (according to what she gets back as a credit). If you are truly splitting the time with your son 50-50, then you should have a written agreement through the court that addresses dependency and day care credits.