Excel 2007 : I need a formula to calculate six months at a time from separate sheet tabs

[VMS]

Hello to all!

I am working on a spreadsheet that is set up as a calendar. Each tab is a new month. In each month under each date in the note area is a list of names that are coded with a number.
Example: Bryant 1, Collins 2, Franklin 4, Harris 5 etc.

The formulas in the master sheets count in each month how many times a name shows up with the coresponding number and will put it in the master sheet column for that number.
Example: the formula is a countif (=COUNTIF(Jan!$A$1:$H$20,"Bryant 1")+COUNTIF(Feb!$4:$16,"Bryant 1") etc.
This will tell me how many times Bryant was coded a 1 in January. (1 is absent excused)

So far everything works fine. Now what I need to do is only have it count a rolling six months at a time.
For example: starting July 1st I want the formula to count only the months from Jan through June. (Remember the months are on separate sheet tabs.) Then on August 1st I need it to change the count and only count from Feb through July, then in Sept count only March through August, etc.

I am stump on how to do this. I have looked at what has been posted for a rolling calendar but I don't think that would work because my sheet tabs are each month.

I know I could put a formula in a column for a six month period and then have the next column carry the next six month period but I do not want that many columns (this calendar will be carried over into another year).

I have attached the calendar to this post if you don't understand my question/problem.
Attachment 159784

Any suggestions? Can anyone help me with this?

[Cutter]

Hello VMS. Welcome to the forum. Unfortunately you haven't followed the Forum Rules. Please click on the Forum Rules button at the top of the page and pay particular attention to rule #1. I'm sure once you've amended your thread title you'll get the help you need.