If you and your BF are the little boy's parents and you all live together only one of you can claim your son. The other parent cannot enter anything about him on their return.
If you are not legally married you cannot claim your child "together." Only legally married couples can file joint returns.
You could try your returns both ways to see which one comes out better for claiming him. And if your brother is your dependent----you should claim your brother.
**Disclaimer: Every effort has been made to offer the most correct information possible. The poster disclaims any legal responsibility for the accuracy of the information that is contained in this post.**
