You chose to calculate a date of April 31, 2007, which doesn't exist.
Assuming that January 55 really means February 24 is not unreasonable.
So I'd call it a feature.

--
Kind regards,

Niek Otten

"Jon McP" wrote in message
...
In the Date function if you take 31/03/2007 and add 1 month to it:
=DATE(YEAR(ref),MONTH(ref)+1,DAY(ref))
you get 01/05/2007, which really isn't 1 month later. Bug or feature?