I just found out that when using DATEADD with business days, if the date being added to is not a business day, DATEADD adjusts it to the next business day, then does the addition. Keep in mind that if you use a holiday file, holidays are not business days.

For example, if I add 2 business days to Jan 1st, 2008 (which is in my holiday file) you get Jan 4th, not Jan 3rd. This is because DATEADD adjusts Jan 1st to Jan 2nd then adds 2 business days.

Likewise, if I add 2 business days to Nov 1, 2008 (which is a Saturday), I get Nov 5th, not Nov 4th. This is because DATEADD adjusts Nov 1 to Nov 3rd then adds 2 business days.

I opened a problem report with IBI and found out this is an undocumented feature of the DATEADD function, not a bug.

I was wondering, for those of you with the manual about using dates (I don't remember the title but it was something like "1000-and-1 ways to use Dates" or "Everything you wanted to know about dates and but was afraid to ask"), is this feature documented there?

On page 123 of Almost 1001 Ways to work with Dates...it says the BD Letters instructs the DATEADD function to adjust the date by business-days which are Monday thru Friday.

-SET &RUNDT1=DATECVT(DATEADD(DATECVT(20080101,'I8YYMD','YYMD'),'BD',-2),'YYMD','I8YYMD');
-SET &RUNDT2=DATECVT(DATEADD(DATECVT(20080101,'I8YYMD','YYMD'),'BD',2),'YYMD','I8YYMD');
-TYPE &RUNDT1  &RUNDT2