Automatically format only those month-cells, that are 3 months ahead of chosen month

Dear all,

I am struggling with another Excel problem, which I will explain shortly.
I am asking my employees to hand in sales forecast for new products that are being launched. I only want them to fill out a forecast though for the first 3 months from the launch month.

I now developed an example spreadsheet, that I attached.

It should work as follows:
1. The employee should select the Launch Month (e.g. February) via a drop down menu in Column A.

2. Now, conditional formating, should make only the months March, April and May (3 months ahead of February White) and the months January, February, June, July etc to December Grey. The employees then understand that they only have to fill out March, April, May.

If the employee selects November as Launch Month, only December, January and February should be White. The rest should be grey.

Does anyone know how to solve this issue?

Much appreciated!!

Best, Alinda

Hi Alinda

Please see the attached file (I have started from your example and attached some rows) which I hope does the trick.

There are basically three steps in my solution
1) (Important) You have to enter the months as numerical (not text) values in order for Excel to be able to judge which months are within 3 months or not. I e you must enter month as 2012-01, 2012-02, 2012-03 instead of "January" , "February", "March" etc.

2) Create a formula that calculates the difference between launch-month and forecast-mont

3) Use of conditional formatting based on the formula in 2)

Good Luck!