There are countless articles and various government agencies reporting on how this ancient system is still in use. Eg. https://www.finance.senate.gov/imo/media/doc/finance_r_lette... https://www.gao.gov/blog/irss-efforts-modernize-60-year-old-... https://www.cfodive.com/news/irs-relies-64-year-old-software... etc etc