If My son stayed with me for 6 months and 6months with his mom. She claimed him on her taxes for the 6months that she had him. How do I claim him for my portion?

[Vanessa · Accepted solution]

When you claim a child, you are claiming them for the year.  Two people cannot claim a child in the same tax year.  

If there is not an agreement on who can claim him, your options are to not claim him this year or to print and mail your return then the IRS will use the Tie Breaker Rules to determine which one of you get to claim him.

[macuser_22]

There is no such thing in the Federal tax law as 50/50, split, or joint custody.  The IRS only recognizes physical custody (which parent the child lived with the greater part, but over half, of the tax year.  That parent is the custodial parent; the other parent is the noncustodial parent.)

Who can claim the exemption and credits depends on who is the custodial parent. (By the IRS definition of custodial parent for tax purposes - this is not the same as the legal custody that a court might grant.).

The test that the IRS uses to determine the custodial parent is where the child lived for more than 1/2 (or greater part) of the year. The IRS will go so far as to require counting the nights spend in each household - that person is the custodial parent for tax purposes (if exactly equal and more than 183 days - The custodial parent is the parent with the highest AGI, if less than 183 days then neither parent has custody so the child cannot be claimed by either parent). And yes they are that picky.

See Custodial parent and noncustodial parent  in Pub 501

<a rel="nofollow" target="_blank" href="https://www.irs.gov/publications/p501#en_US_2018_publink1000220906">https://www.irs.gov/publications...>
 
Only the Custodial parent can claim: (Child would be listed as non-dependent EIC & CC only)
-Head of Household
-The Earned Income Credit
-The Child and Dependent Care Credit
-The Health Coverage Tax Credit

The non custodial parent can only claim: (Child would be listed as dependent)
- The child as a dependent
- The Child Tax Credit or credit for other dependents

But only if specifically specified in a pre-2009 divorce decree, separation agreement or the custodial spouse releases the exemption with a signed 8332 form - after 2009 the IRS only accepts a signed 8332 form that must be attached to the non-custodial parents tax return.