This form is to be filled out within 72 hours of departure to Turkey to get HES code. (Turkey websites)
However US Counsalate Turkey indicates that as of April 20 it was not.
Confusing messages.
Anybody know?
I don't know. We had to fill one out last November, but things are changing rapidly. They very well could have dropped the requirement recently.
The Istanbul Airport site says that it's still required and https://hayatevesigar.saglik.gov.tr/hes-eng.html is still talking about it, but the Turkish Airlines site doesn't mention it.
As I recall, it was no big deal to fill it out. I am returning to Turkey next month, and I'll probably fill it out just to be on the safe side.
UPDATE: I am not 100% sure, but it looks like you still have to fill out the health form at https://register.health.gov.tr 72 hours before entry, but the site no longer generates a HES code. I'm not sure what they do with form.
Marie's update is the latest I've read: the health form is still required, but the HES code is not generated as it's no longer required for linking to things like transit passes.
Per the Turkish embassy, as of March 2, "HES code requirement has been lifted in all institutions and entities."