I have tried to find an answer to this question on both the Insiders site, as well as the Marriott Rewards page, without success so I'm hoping an Insider can help me out.
If you have a Rewards Certificate with an upcoming expiry date, can you use it to book a stay after the expiry date or does the stay have to be completed before the certificate expires? For example, if my certificate expires May 13, 2013 can I use it before the expiry date for a stay to take place on June 2, 2013?
Your stay would have to take place by the expiration date of the certificate. You may try contacting Marriott Rewards customer service and see if you can possibly get an extension. Last year I need an extension for the Credit Card certificate I had earned and a Marriott Rewards agent contacted Chase and I got an email a couple of days later stating that my certificate date had been extended.