"One FlyerTalk user reported using the IBM corporate code for 14 years, 80–100+ nights a year, and never once being asked for ID. However, Newark Airport Marriott religiously asks for ID, requiring a letter from IBM stating you are a legitimate contractor. Consultants who tried to use a former employer's IBM code and couldn't produce valid ID were charged the full going rate of ~$300 instead of the corporate rate of ~$100."

"I have been asked to show some proof couple of times. I normally show my corp id but credit card with employers name on it has worked, too. As would probably just showing my laptop with employer e-mail account or whatever. My impression has been they are happy with just about anything that proves I'm working for the company whose rate I use and why wouldn't they."

"I now always make it a matter of course to carry documents (business cards of my contacts, e-mails requesting my visit etc.) from my host company when I travel. This has always proven sufficient for the few times I've been challenged by the front desk clerk."