BACKGROUND: First, my wife and I are "Mom & Pop" landlords. Second, I am not good with computers. Recently I learned that my computer had Excel 2003 pre-installed when I bought the computer---so, I went to Library and read through 3 books on Excel 2003. To make things easier for my wife (she keeps the records), I was able to set up a "Rental Income" file for year 2007----there are 12 spearate "books" in the file, --one "book" for each of the 12 months (Jan, Feb, etc). Most of the time tenants pay the full balance due each month. HOWEVER, occasionally, a tenant does not pay all balance due. My my wife says that there should be a way to have the Excel program communicate data between "books.---Specifically, for example, if all rent is not paid in January, that fact and the balance remaining/due should be automatically brought forward in to the next month (e.g., Feb) --She suggest that it be automatically brought forward to the next month-- in a field labelled: "Previous Balance Due." QUESTION: Is there a way to communicate data between "books" (in this case, months of the year) in an Excel 2007 file??? Telling me the exact steps would be great---or, referring me to a book would be a good 2nd alternative. (Again I've read 3 books, including "Excel 2003 for Dummies"). Any help would be most appreciated. Jaes.