I once did it at 100 days and was approved, iinm the date of incident has to be within 90 days but you can file the claim some while after too
Interesting data point, and based on the inconsistencies (and sometimes typos and other errors) that I've seen in the letters they send out, I can believe that they sometimes either miscount the days or fail to count them at all. But the official policy (quoting from the PDF linked to the U.S. Platinum card) says:
"Once you have verified that the merchant will not accept the eligible item, call 1-800-228-6855 within 90 days of the purchase date to notify us of your request. Within 30 days from the date of your initial call, we need to receive the following:
- A copy of the original store receipt
- A copy of the American Express Card record of charge
- Any other items deemed reasonable by us to process your request"
The key phrase to me is to contact AmEx "within 90 days of the purchase date" to submit a claim, meaning that anything 91 days or more from the purchase date would technically be ineligible. Of course, their official policy, and the terms that they have written in the Program Description PDF, might be two different things. But my interpretation would be that it doesn't hurt to try, as the worst they can do is tell you that the item is no longer eligible for a Return Protection claim, but I certainly wouldn't want to get my hopes up that they'd approve a claim that I submitted more than 90 days after the date of purchase, per the Return Protection Program Description.