A plan with just one employee (thus must file 5500 and not 5500EZ) has $0 compensation and $0 funding in its first year. Is it necessary to file a 5500 with all 0's or can they wait until their first year of actual funding?
Thanks.

File. Exception would only be if this was 5500-EZ (assuming that your one participant is not the owner - I've seen some benevolent plans like this - so you're filing 5500) and assets of all plans were under $100k. Did have a similiar situation with a newly established 401(k) where the client didn't get their act together soon enough for deferrals.

I assume this employee works on commissions, because otherwise, with $0 compensation I wouldn't consider him an employee for the year.

Yes, he's an employee that works on commissions. So we go back to the original issue, is it necessary to file 5500 with 0's? Of course it is no crime to file a form with 0s.