Can i claim my boyfriend's child who lives with me and i support?

[DawnC0]

Yes, but only if the child:

•  Is not the “qualifying child” of another taxpayer (your boyfriend or child's mother)  
•  Earns less than $4,050 in 2016
•  Receives more than half of his total support from you
•  Lived with you all year as a member of your household

http://blog.turbotax.intuit.com/tax-deductions-and-credits-2/family/who-can-i-claim-as-a-dependent-7...