>report them to IRS
here's a handy link, the report is easy. be aware there is a brick wall for the "protected class" is a whole other issue. "Sensitive Case" label is slapped on immediately, referrals are usually refused for little/no reason. Careers have died on the vine for making this kind of effort.
https://www.irs.gov/businesses/small-businesses-self-employed/tax-scams-how-to-report-them