Another checkin time thread...
 

I arrived at the check in counter for my DEN-LAX-KOA flight this morning and was denied check in. While I know I was cutting it close, I got to the counter about 35-40 minutes before the flight. According to UA's website, that shouldn't be a problem.
The CSR told me that I needed to be there with my luggage 1.5 hrs before the flight. When I advised her about UA's website and that I could still make the flight, she told me I was wrong.

She rebooked me through SFO, in Y (I had confirmed upgrades with a CR1), but it looks like F is 0.

I'm just curious about this... shouldn't she have let me check in? I know I was cutting it close, but I was within the appropriate time frames according to the site.

According to http://www.united.com/page/article/0,6722,52481,00.html, the cut-off for checking bags at DEN (and basically all non-regional airports in the U.S.) is 45 minutes.

45 min cut off for checking bags is correct. Same thing happened to me once before where I ended up losing the F upgrade on the domestic segment of my trip. Lesson learned :)

Thanks for the clarification. I knew I got the 30 minutes from somewhere :)

Something similar happened to me at PDX once... I got to the chicken 44 minutes before the flight... Was a little angry that I got denied for being 1 minute late but then fortunately I got put on a direct and got there 2 hours before my original routing^... Sounds like the OP wasn't as lucky though.

Also, the 90 minutes the agent referred to was probably just the generic suggestion of "if you have bags to check, please arrive at the airport 90 minutes before your flight is scheduled to depart", and not the actual cut off time.

If you had no checked luggage, then you need to to obtain a BP 30 minutes prior to scheduled time. Maybe this is the 30 minute rule you were thinking about?