I'm trying to claim my fiancee and her kids, but I can't select head of household why?

[KrisD15]

The child must meet the requirements of being your Qualifying Child for the Head of Household status. 

These requirements are different than those to claim a qualifying child as a dependent. 

"The eligibility of a qualifying child or dependent extends beyond just your own son or daughter. To be considered a qualifying child, the child has to meet the criteria in each of the following categories:

• The child is your biological or adopted child, stepchild, foster child, sibling, step sibling, half sibling, or a descendant (child, grandchild, great grandchild, etc.) of one of these relatives
• The child lived within your home for more than six months during the tax year
• The child needs to be younger than you
• As of the end of the tax year, the child is under 19 if he is not a student, or under 24 if he is a full-time college student
• The child did not pay for more than half of their living expenses during the tax year"

TurboTax Link 

[xmasbaby0]

In order to file as HOH, you have to claim a qualified dependent who is related to you.   If you are not the bio-dad of the children and not legally married to their mother, then the children cannot be qualified dependents for you to use HOH filing status.

If all of them lived with you for the whole year in 2023, at best you can get the $500 credit for other dependents for them.  You do not get child tax credit, earned income credit or childcare credit for them.   You cannot claim your GF if she had more than $4700 of income not counting Social Security.

Am I Head of Household?

https://ttlc.intuit.com/questions/1894553-do-i-qualify-for-head-of-household

https://ttlc.intuit.com/questions/2900097-what-is-a-qualifying-person-for-head-of-household

If you qualify as Head of Household, when you enter your marital status (single or married filing separately) into MyInfo, and then enter your qualifying dependent, TurboTax will offer HOH as your filing status.

https://ttlc.intuit.com/questions/4499708-what-is-the-500-credit-for-other-dependents-family-tax-cre...