I am trying to figure out the due date for new a test, and then copy that
formula straight down the worksheet.

For example
Person A took her inital test on 13 Oct 07, 180 days later the next test is
due on 13 Apr 07. Now I entered the formula =DATE(2006,10+B165[180 days],13)
to give me the next test date due on 13 Apr 07. However when I go down to
the next row to complete the next test date for person B who took his test
initally on a different date: 23 Feb 06, I began to realize that I would have
to individually change the intial test date in the same formula for each
individual person. I have over two hundred people!

My question is this? Is there any way that excel could calculate the next
test date due with the same formula without me having to go into that same
formula on each row and change the intial test date of each person?

Thank you for your help, I look forward to a response from you soon.