Are these persons related to the child?
Are they both parents?
Does the child live with either person more than 6 months during 2008?
Either of you can claim the child - I suggest you to estimate your refund in each situation before making the decision.
Please let me know if you need help in estimating your refund in each situation.
Two persons may not claim the same dependent in the same tax year.
If you do and file electronically - the IRS will reject the second return.
If you disagree and both parents will claim the child - the IRS will allow to the person with largest adjusted gross income and will disallowed to another.
That what would happen if you disagree on who will claim the child.
The first return will be most likely accepted by the IRA automatically, however the second return will be rejected by the IRS on the base that the child was already claimed.
If the second person still insist on claiming the child - he/she would need to main a paper return to the IRS and may be asked to attach supporting documents that he/she is eligible to claim the child.
In case both persons are eligible to claim the child - the IRS would apply the tie-breaking rule - if two of the persons are the child's parents, they do not file a joint return together, and the child lived with each parent the same amount of time during the year, THEN the child will be treated as the qualifying child of the ... parent with the higher adjusted gross income (AGI).