I have had custody of a child since March, is there a way to submit the social security number so that no one else files and claims them? I have custody thru the courts.

[DoninGA]

No, there is no way to prevent someone from entering a Social Security number on the tax return that they file.  

[macuser_22]

Court ordered custody has nothing to do with claiming a dependent on a tax return. 

The tax law rules for a "Qualifying Child" dependent requires that child must have physically lived with you more than 1/2 the tax year and must be your son, daughter, stepchild, foster child, brother, sister, half brother, half sister, stepbrother,stepsister, or a descendant of any of them.   

If the child that lived with you since March is not related to you in one of the above ways then you cannot claim the child as a dependent at all because the other the other type of dependent (Qualifying Relative) requires that that person lived with you the entire year plus other requirements if not closely related.

[Carl]

When it comes to federal taxes, understand that "how" or "why" you have custody of a minor doesn't matter to the IRS. If that minor is a blood relative they have to qualify under the "qualifying child dependent" rules of the IRS for you to claim them as your dependent. Just because you may have been awarded custody by the court, doesn't mean they will qualify as your dependent.

If the minor is a non-related child, then they have to qualify under the "qualifying relative dependent" rules of the IRS.  They don't have to be an actual "relative" per-se. But those are the rules which apply to a non-blood related minor you wish to claim as a dependent on your tax return.

For a "plain english" definition of the rules see https://www.1040.com/tax-guide/taxes-for-families/who-can-you-claim/

[xmasbaby0]

@dgoble1965 Since you have not told us how or if the child you are taking care of is related to you, please post back with that information.  If in fact the child is related to you, then you may be able to claim the child as a dependent.    And in the event that someone else tries to claim that same child, we can tell you what to do.  Please clarify what your relationship is to the child.