If a cafeteria plan has a short first plan year, are the contribution limits prorated? For example, if the first plan year is 11/1 to 12/31, are deferrals for DCA limited to $800 rather than $4,800?

That depends on what the document says. Most sponsors will put something in the document and the SPD which talks about pro-rating. If the document is silent, you have to assume that there is not prorating.

You might also confirm that your document limits your dependent care FSA to $4,800. Why not allow the entire $5,000 permitted by Section 129?

Does a plan year have to match a calendar year? For example, can I run a plan year for the flexible benefits from 7/1 to 6/30 of the following year or do I have to stick with 1/1 to 12/31?

Walter,

It is my understanding that you can use a fiscal year for some 125 benefits plans. However for tax reporting purposes using the tax/calendar year is simpler.