Texas. Non-custodial father says he wants to move out of state.

I'm the mother and the custodial parent. I have our two kids (ages 12 and 8) 56% of the time and their Dad, the non-custodial has them 46% of the time.

He wants to move out of state from Texas to Tennessee for a work opportunity. He is paying the maximum 25% child support now.

Is he allowed to do this by law? And can I get more child support out of them? He just wants to see them for 2-4 weeks a year in the summer I believe.

Please don't give comments about him being a dead-beat etc, I'm not interested in bitching about men. I just want to know where I stand legally. Thanks! :)