Myrna Larson wrote...
The usual way is =DATE(YEAR(A1),MONTH(A1)+1,DAY(A1))
....

?

If A1 were 31-Jan-2005, the formula above most definitely DOES NOT give
28-Feb-2005.

To return the corresponding day of the subsequent month, where, e.g.,
31-Jan would correspond to 28-Feb in non-leap-years, use

=A1+31-MOD(DAY(A1+31)-DAY(A1),DAY(A1+63-DAY(A1-DAY(A1)+63)))

or

=DATE(YEAR(A1),MONTH(A1)+1,MIN(DAY(A1),DAY(DATE(YE AR(A1),MONTH(A1)+2,0))))