The non Custodial Parent lives in another state. He is collecting Social Security and they are reducing my child support amount because of that, however he is working under the table, even admits it on email, and he is buying and selling cars for extra money (I have copies of the ads). Child Support Enforcements says if he is not paying taxes on income they can't count it. Isn't it illegal to work under the table?

No, its not illegal to "work under the table". It IS illegal to not report income earned to the IRS. So, you can threaten to turn him into the IRS. But if he goes to jail what happens with your income?

The non Custodial Parent lives in another state. He is collecting Social Security and they are reducing my child support amount because of that, however he is working under the table, even admits it on email, and he is buying and selling cars for extra money (I have copies of the ads). Child Support Enforcements says if he is not paying taxes on income they can't count it. Isnt it illegal to work under the table?
So lets say I don't necessarily turn him in for tax evasion, but report his employer for tax evasion and hope he coughs up the records...

That might get him fired.

The non Custodial Parent lives in another state. He is collecting Social Security and they are reducing my child support amount because of that, however he is working under the table, even admits it on email, and he is buying and selling cars for extra money (I have copies of the ads). Child Support Enforcements says if he is not paying taxes on income they can't count it. Isnt it illegal to work under the table?
Wow, its amazing, that our system allows for people to evade supporting their children, tax evasion, cause no one wants to pursue it and they get off scot free.