Can I allow my live-in girlfriend of 3 years to claim my son as a dependant?

[sam_ealy]

The mother of the child is not present in the child's life as of right now and my girlfriend helps financially and emotionally support my son while I am often away at work.

[DoninGA]

For the child to be claimed as a non-relative dependent under the Qualifying Relative rules they would have to meet all the requirements under the rules.

To be a Qualifying Relative -

1. The person cannot be your qualifying child or the qualifying child of any other taxpayer. A child is not the qualifying child of any other taxpayer if the child's parent (or any other person for whom the child is defined as a qualifying child) is not required to file an income tax return or files an income tax return only to get a refund on income tax withheld.
2. The person either (a) must be related to you or (b) must live with you all year as a member of your household.
3. The person's gross income for the year must be less than $4,300 (social security does not count) in 2020
4. You must provide more than half of the person's total support for the year.
5. The person must be a U.S. citizen or a U.S., Canada, or Mexico resident for some part of the year.
6. The person must not file a joint return with their spouse.

[fanfare]

Since the child is a dependent of you, a parent, she can't claim him.

[xmasbaby0]

If your GF claims the child --- who she is not related to -- all she "gets" is a $500 credit for other dependents.  She cannot file as Head of Household  or get earned income credit or the child tax credit for claiming your child.  You, as the parent, can get all of the child-related credits and if you pay at least half the household costs you can also file as HOH.