Are employees of corporations that only have a profit sharing plan eligible for the additional contribution amount if they are over 50?

Not unless the plan has a 401K elective deferral feature. The catch-up contribution is an extra salary deferral.

Absent IRS guidance, this issue is not easily resolved. Patrick Foley's post states the most likely resolution of the issue, but other reasonable interpretations exist.

The "applicable employer plan" definition of Code Section 414(v) is not limited to plans that accept traditional elective deferrals. It is possible to interpret Code Section 414(v) to allow an employer with a profit-sharing plan w/o a cash or deferred arrangement to accept catch-up contributions.

This issue is particularly urgent for the IRS to resolve because if one allows catch-up contributions for some participants, then the whole "employer" must allow catch-up contributions for all participants. If there are some participants who aren't eligible for 401(k) plans but are in other types of retirement programs, employers right now don't know whether they'd also have to be allowed to make catch-up contributions.

I'd be interested if others think I'm off base here. I like Patrick Foley's simpler answer better than my own!

I just read another post that also addresses this same topic:

http://benefitslink.com/boards/index.php?showtopic=11085