This question's underlying motivation is disgusting; you should be ashamed of posting such a dog-whistle. Anyway, just tie it to tax-return information, as Cali

This question's underlying motivation is disgusting; you should be ashamed of posting such a dog-whistle. Anyway, just tie it to tax-return information, as California is doing; if one doesn't pay taxes, then one can't claim the benefit. Nobody cares about "illegal" status, just about whether folks are working and paying taxes.