I have a daughter and I am not married to her father but we live in the same house. How would I go about claiming her?

[xmasbaby0]

If you all live together as a family, then your child can only be claimed on ONE tax return.   It is usually better for the parent with the higher income to claim the child, but that can vary with other circumstances.  Please provide some details.

[Opus 17]

When two parents who are not married, live together and share a child, then either of the parents can claim the child as a dependent, but not both.  There are certain procedures for "splitting" the tax benefits of a dependent, but those only apply when parents live apart and share custody.  When the parents live together, one parent can claim the child and all tax benefits, and the other parent claims nothing.  In Turbotax, the parent who will claim the child should say the child lives with them the whole year, and answer "no" to any questions about custody agreements (because that only applies to legal agreements between parents who live apart and share custody).  The parent who will not claim the child should not even try to list them on their tax return.  

If you are the parent who pays more than half the total household expenses and you claim the child, you can also claim head of household status, which has lower tax rates than single.  The other parent files as single with no dependent.  If the parent who pays less than half the expenses claims the child, that parent files as single, and the other parent also files as single because they cant claim head of household without a dependent.   (More than half only needs to be $1 more than half.  If both parents pay exactly half the expenses, no one can use head of household status, because exactly half is not more than half.)

It is usually better for the parent who pays more than half the living expenses to claim the child, but the only way to know for sure is to test both combinations.

[DoninGA]

Only you as the mother of the child can claim the child as your dependent under the Qualifying Child rules.  You are the only one that can claim the Child Tax Credit on a tax return.  Since you are not legally married you can only file as Single or you may be able to file as Head of Household if you are eligible.

See this TurboTax support FAQ for Head of Household - https://ttlc.intuit.com/turbotax-support/en-us/help-article/tax-filing-status/qualify-head-household...

To be a Qualifying Child -

1. The child must be your son, daughter, stepchild, foster child, brother, sister, half brother, half sister, stepbrother, stepsister, or a descendant of any of them.
2. The child must be (a) under age 19 at the end of the year, (b) under age 24 at the end of the year and a full-time student or (c) any age and permanently and totally disabled.
3. The child must have lived with you for more than half of the year. Temporary absences while away at college are considered living with you.
4. The child must not have provided more than half of his or her own support for the year.
5. If the child meets the rules to be a qualifying child of more than one person, you must be the person entitled to claim the child as a qualifying child.
6. The child must be a U.S. citizen or U.S., Canada or Mexico resident for some portion of the year.
7. The child must be younger than you unless disabled.

If the other person is not the biological father of the child they have to file as Single.  Depending on your circumstance they may be able to claim you and the child as dependents, but only under the Qualifying Relative rules.  And they would only be eligible for the Other Dependent Credit of $500 for each of you.

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 $4,700 (social security does not count) in 2023
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.

[NCperson]

@599f9ae91615 -simple answer 

as you two are the bio parents, either of you can claim the child 

if you can't agree, and assuming you all lived together all year, whomever  has the higher income claims the child. 

[xmasbaby0]

"I have a daughter and I am not married to her father but we live in the same house."

This sounds as if both parents living with the child in the house are the biological parents.  @599f9ae91615 Is that correct?   Are both of you the parents of the child?

[Hal_Al]

 If you and the other biological* parent live together, either one of you (but not both) may claim the child. You may decide between you which one will claim the child. Only if you can’t agree, do the IRS tie breaker rules apply, to see who has first choice. The first rule is the parent the child lived with the most. If that is the same (you all three lived in the same house all year), then it's the parent with the highest income (AGI). 

It may be worthwhile to prepare trial returns, both ways,  to see which way the family comes out best. This tool may be useful: https://turbotax.intuit.com/tax-tools/calculators/taxcaster/?s=1.