When you give the money to him, it is considered a gift and you are subject to gift tax. Of course, this year's exemption is $5,000,000. The $500,000 you would give to him will nevertheless count against that lifetime $5,000,000. A simple math is if the estate tax remain as high as right now and you end up having more than $5,000,000 when you pass away, you would leave about $200,000 less for your children.