Hello, I just noticed that the Windows time zone for "UTC +03:30 Tehran" is probably being computed incorrectly. It seems that DST +1 is being added, although Iranian Government announced that they will not switch to DST anymore, beginning in 2023. Official IR News Agency announcement: http://irna.ir/xjJ3TT Current Time: https://time.ir I assume that Microsoft imports IANA time zone data: http://bit.ly/3ZmGzTE In the file tzdata2023b\asia on line 1625 it says: 3:30 Iran +0330/+0430 I assume the line should be changed and a new line should be added, e.g.: 3:30 Iran +0330/+0430 2022 3:30 - +0330 More ressources: http://bit.ly/3lQC9qp https://www.timeanddate.com/worldclock/iran I am looking forward to any feedback. Thanks a lot, Patrick