Does a legal guardianship qualify the child as my child for taxes

[xmasbaby0]

We need more information.   You have not mentioned if the child lived with you in 2021 or for how long the child lived with you.

IRS interview to help determine who can be claimed:

https://www.irs.gov/help/ita/who-can-i-claim-as-a-dependent

https://ttlc.intuit.com/questions/3113432-who-can-i-claim-as-my-dependent  

[Mike9241]

maybe.

here are the tests you must be for being able to claim him/her

1) You’re related to the child (brother, sister, half-brother/sister, stepbrother/sister, father, mother, grandparent, or other direct ancestor, stepfather/mother, son or daughter of the taxpayer's sibling or half-sibling). if you are not related the child must have lived with you in your household for the entire year (temporary absences like school are ignored)

2) their gross income for 2020 is less than $4,300. for 2021 $4350
3) you provided over ½ the support for the child for the tax year 

4) you yourself can't be a dependent of someone else (regardless of whether they actually claim you)

[Opus 17]

If the child is placed in your home by a state foster agency or other state legal process (court order, etc.) then you have the same status toward claiming the dependent as a biological parent.  The Turbotax dependent interview should include "foster parent", use that.

That said, there are other tests to claim a child including residency and support that you would have to meet.