Marriott doesn’t have blackout dates. Award redemption is permitted on all dates. However hotels are allowed to have significant capacity controls for a handful of dates each year. Marriott is increasing the number of hotels that are allowed to limit award redemption at their busiest times.
Marriott made a change to its terms and conditions and it’s no longer only Marriott brands that can declare high demand dates where award redemption is limited. These redemption controls are now available in 2020 to all hotels within Marriott, including ex-Starwood properties.