Hi Rob,

I'd be happy to help you with this task in Excel!

Here are the steps to determine if a month falls between two dates and return a value of X:

1. In cell C2, enter the formula:
   Formula:

   =IF(AND(MONTH($A2)<=MONTH(C$1),MONTH($B2)=MONTH(C$1)),"X","") 

2. Copy the formula in cell C2 to the range C2:N2. You can do this by selecting cell C2, then dragging the fill handle (the small square at the bottom right corner of the cell) to the right until you reach column N.
   
3. Copy the formula in row 2 to the remaining rows in the table. You can do this by selecting cell C2, then dragging the fill handle down to the last row of your table.

This formula uses the IF function to check if the month in the column header (C1:N1) falls between the start date (column A) and end date (column B) for each row. If the month falls between the start and end dates, the formula returns "X". Otherwise, it returns an empty string ("").