From the New York Times:

Adding to the pain: A hodgepodge of data storage systems that do not communicate with each other has handicapped customer service workers at the I.R.S., who often cannot determine why a tax return has stalled in the process.

Technology is often a symptom and not a cause of the pains an agency faces. The IRS technology being outdated is not why they’re struggling, it is the lack of funding. The technology becomes outdated because of that lack of funding and inability to recruit and hire technical talent.