I pay for the lease of 2 different addresses, my child and his mother officially reside at one residence, and I officially reside at the other. However I spend an equal amount of my time at both places, and pay all rents and pay for everything to allow my girlfriend to be a stay-at-home mom. She does not have any other job, and relies on me for all finances.

Can I file as a head-of-household with my official address? Or do I need to use her official address?

Zoltan