Adjust for Daylight Saving Time

Tableau has this Knowledge Base article on how to adjust a date field for Daylight Saving Time (DST).  However, after further testing, I found the formulas have some bugs.

 

Above are test scenarios for Daylight Saving Time adjustments in America and Europe.  The Datetime ‘OLD’ column used the (incorrect) calculated field from the KB article, whereas the Datetime ‘NEW & BETTER’ column used the (correct) calculated field below.  Notice the datetimes with red dot are the ones with discrepancies in the time adjustment.

 

Here’s the correct calculated field to adjust for DST in the USA:

 

 

 

 

 

 

And here’s the correct calculated field to adjust for DST in Europe: