I have 2 children that I would like to claim that are not mine biologically. My fiancée and I have lived together for 4 years. Can I claim them as My Children?

You have to choose Other since you are not related to the children.

If they are not your own bio-children you cannot say they are..   You may be able to claim them as "other dependents" for the $500 credit for other dependents, but that is all.  You do not get to file HOH, get child tax credit, earned income credit or childcare credit by claiming them. That would change if you were legally married and were the legal step-parent.

 

WHO CAN I CLAIM AS A DEPENDENT?

 

You can claim a child, relative, friend, or fiancé (etc.) as a dependent on your 2023 taxes as long as they meet the following requirements:

Qualifying child

• They're related to you.

• They aren't claimed as a dependent by someone else.
• They're a U.S. citizen, resident alien, national, or a Canadian or Mexican resident.
• They aren’t filing a joint return with their spouse.
• They're under the age of 19 (or 24 for full-time students).
• No age limit for permanently and totally disabled children.
• They lived with you for more than half the year (exceptions apply).
• They didn't provide more than half of their own support for the year.

Qualifying relative

• They don't have to be related to you (despite the name).
• They aren't claimed as a dependent by someone else.
• They're a U.S. citizen, resident alien, national, or a Canadian or Mexican resident.
• They aren’t filing a joint return with their spouse.
• They lived with you the entire year (exceptions apply).
• They made less than $4,700 in 2023.
• You provided more than half of their financial support.

When you add someone as a dependent, we'll ask a series of questions to make sure you can claim them. There may be other tax benefits you can get when you claim a dependent.

Related Information:

• What does "financially support another person" mean?
• What is a "qualifying person" for Head of Household?

No.  One of the rules to claiming a non related child is that they cannot be the qualifying child of another taxpayer.  Since their mother is able to claim them, you cannot claim them as a dependent and is filing a return. 

 

"A child isn't your qualifying relative if the child is your qualifying child or the qualifying child of any other taxpayer." 

 

To claim someone as a Qualifying Relative, they must be:

• Your child ( including step children, adoptive children and foster children) or a descendent of them
• Your sibling (including half siblings) or a child of your sibling or a sibling-in-law
• Your parent or grandparents, including step parents and in laws
• Any other person that lived with you for the entire tax year
• Not a qualifying child of another taxpayer
• Someone that you provided over half of their support for during the tax year
• Has less than $4,700 in income (not counting social security)

If the childs mother is only filing a return to get a return of withholdings and is NOT required to file a return, then yes, you would be able to claim them as dependents.  If she is required to file, then no, you cannot claim them. 

 

(Edited 2/17/24 @ 12:20PM) @ctrojacek

Not as your children but If you paid for more than half of their support as members of your household throughout the year, you can claim them as Qualifying Relatives. They would be your dependents to claim for tax purposes.