Three major hotel chains have changed their cancellation policies over the summer. The changes were rolled out rather suddenly and with very little to no notice. We've certainly had plans change at the last minute or flights cancelled, and it's good to know one's options in these situations. The changes only affect new reservations, though they are worth remembering when booking hotels either with cash or points in the future.
IHG -Changed from 6:00 p.m. day of cancellation (local time to hotel) to current language that shows 24 hours cancellation; currently it's very vague from IHG as to when the 24 hour mark is measured. Some regions like China will still continue to have same-day cancellations.
Hilton- Changed from 24 hours to 48 - 72 hours. Check your exact time at booking, the Hilton website will display the cutoff time for free cancellation. Most properties are going to 48 hours, a few will have the (more draconian) 72 hour policy.
Marriott- Changed from one day to two days. You used to be able to cancel up until midnight (hotel local time) the day before your arrival. Now, you'll need to do so at least two days by midnight in advance.
H/T to Travelweekly