www.irs.gov/newsroom/irs-increases-visits-to-high-income-taxpayers-who-havent-filed-tax-returns
taxlitigator.me/2020/02/19/high-income-non-filers-are-back-in-sights-of-the-new-enforcement-minded-irs-by-steven-toscher-and-gary-markarian/
Update:
www.gtlaw.com/en/insights/2021/6/the-irs-announced-a-new-non-filer-initiative-over-a-year-ago-now-we-see-the-enforcement