I was told prior to Yom Kippur we greet with גמר חתימה טובה and post just גמר טוב.
Someone corrected me saying the final signing is Hashanah Raba and therefore we still useגמר חתימה טובה.
Is it all minhag and no way is completely correct?
The signing of the decrees is on Yom Kippur, as we say in Nesane Tokef “u’byom tzom kippur yechaseinmu”, and that is why we say v’chasom” during neila. On Shemini Atzeres is when the “messengers” go out with the decrees, therefore before Yom Kippur we say a גמר חתימה טובה, but after that we just say גמר טוב.
Have a gut Yom Tov