"KRK" wrote:
How do I add 1 calendar month to a date, regardless
of the number of days in the month?

Depends on what you want for "one month after Jan 31", for example.

For most purposes, the preferred answer is Feb 28 (or 29 in leap years). In
that case, use EDATE(A1,1). If you get a #NAME error, see the Help page for
EDATE.

If Mar 2 (or 3) is acceptable, use DATE(YEAR(A1),1+MONTH(A1),DAY(A1)).