If we want to submit a research abstract or any scholarly work through Harvard’s portal, is there a deadline for this?
As I read it, their deadline for your application-- the whole application, I would assume-- is today.
You’ve asked at least four questions about an abstract dating back several months, so I need to assume it’s done. Just assume that there is not a later deadline and submit it when the rest of the application is due. Then forget all about it and focus on the last few months of HS, at least until the end of March rolls around.
Harvard will start reading an application then all the required components are in. If non-required elements come in after the first read, they will be added to the file. How much time will be spent looking at new elements after the first read is unknown to any of us, so if supplemental info is important to you, don’t risk it only receiving a cursory glance by sending it late.