"GM's Marriott code GMC is confirmed in FlyerTalk's publicly usable codes list alongside Ford (FRD) and Toyota (TOY). No specific verification-denial threads were found. General Motors has major hubs in Detroit/Metro Michigan, and Marriott properties near the Renaissance Center likely handle many genuine GM employees. US verification is rare — geography matters most, with hotels within 5 miles of GM's corporate HQ being the exception."

"I have been a Platinum for a few years (which implies I frequent Marriott properties on a regular basis) and up until tonight was NEVER asked for any id to justify a corporate rate or discount (I legitimately use a few corporate rates I am entitled to and AAA rates)"

"GAP Inc's Marriott code GAP is listed in corporate code databases. No verification incidents documented in FlyerTalk or Reddit discussions. Clothing retail corporate codes at Marriott receive minimal attention from front desk staff — retail employee IDs are not standardized enough to be reliably verified. US domestic properties rarely verify retail-sector codes."