I looked into it more deeply, and I found that apparently what happened is that he was laid off five years ago, and no one ever told him about it.
10 seconds sound clip from the Office Space movie soundboard.
You can hear this line at 00:39:25 in the Blu-ray version of the movie.
Quote context
[...]
- You know, squirrely-looking guy. Mumbles a lot.
- Yeah, we we can't actually find a record of him being a current employee here.
- But through some kind of glitch in the payroll department, he still gets a paycheck.
- So we just went ahead and fixed the glitch.
- Well, just a second there, professor.
[...]