@Periklis **************
You should not rely on a wrong assortment given to you by a misinformed Immigration officer.
You should refrain from thinking in terms of "calendar year".
I would rather say that all visa-exempt stays within the recent "1-year period" will be taken into consideration when you attempt several visa-exempt entries or several applications to an extension
Just think about it mathematical:
WHY would they really count in "calendar year"?
This would allow you 157 days BEFORE New Year, and 157 more days AFTER New Year, totaling in a 304-days consecutive visa-exempt holiday inside Thailand.
304 days of a holiday without a visa? Really?
The mind boggles.
It is not accurate that the Thai Immigration counts in "calendar years". Never ever.
It won't make much sense. With absolute certainty, the count is “per one-year period”