In article .com,
"Harlan Grove" wrote:

Chip's formulas work, but they're longer than necessary. The 2nd and
4th Wednesdays in the month containing the date given in A3, one could
use

=A3-DAY(A3)+14-WEEKDAY(A3-DAY(A3)+5,3)

and

=A3-DAY(A3)+28-WEEKDAY(A3-DAY(A3)+5,3)

Might could even make it a bit shorter:

2nd Wed:

J1: =A3 - DAY(A3) + 14 - WEEKDAY(A3 - DAY(A3) + 5, 3)

4th Wed:

J2: =J1+14