Treasury's master business file, which contains all tax data on individual business income taxpayers, likewise is written in that same assembly language code, which was first used in the 1950s, and maintained on the old-school IBM mainframe.
While Treasury has general plans to replace the systems, "there is no firm date associated with the transition," GAO's report said.
In addition to Defense, the departments of Treasury, Commerce, Health and Human Services and Veterans Affairs "reported using 1980s and 1990s Microsoft operating systems that stopped being supported by the vendor more than a decade ago," GAO said.
And the Social Security Administration "reported rehiring retired employees to maintain its" systems which use COBOL, the computer programming language which was widely used — in the 1970s — according to GAO.
COBOL is also used by the Justice Department in its program to provide information about prison inmates, and the VA, which uses it for employee timekeeping and to track veterans' benefits claims and dates of death, the report said.