Claiming Dependents

I have always claimed my kids as dependents.  This year, they both still qualify as dependants, and when I look through Turbotax, I get a $500 credit per child.  When I review my oldest son's income taxes, he gets $1100 more back by me not claiming him, and claiming himself.  The money would say do it that way.  Am I required to claim my son if he meets the criteria to be claimed?  I thought I read in the past that if I can claim them, I'm required to.  Thanks.