We just got 3rd party custody of our grandchild and was wondering if we can claim her on our taxes

[SweetieJean]

"just got" Exactly when? and where did she live previously?

[happyinwm]

we just got the legal papers this year but she has been with us off and on last year

[SweetieJean]

How many nights did she stay with you in 2017? Were her parents there as well?

[viktoriyab11]

Yes, you can claim your grandchild on your tax return if all dependency rules applied. 

Who can I claim as my dependent?

Please, follow this link for more information about the Tie-Breaker Rules https://ttlc.intuit.com/replies/6489993