The U.S. Postal Service and the members of the Citizens’ Stamp Advisory Committee (CSAC) have revised certain basic criteria used in determining the eligibility of subjects for commemoration on all U.S. stamps and stationery.
Effective in 2018, “Living people will not be considered at the present time. Beginning in 2018, proposals for a deceased individual will be considered three years following his/her death.”
Prior to this change there was no waiting period after the death of an individual since 2014. Before that, the waiting period was ten years.