You can use Conditional Formatting for this:

Select the cell containing your actual cost. I'll assume cell B1 for this
example, and that cell A1 contains your budget amount.

From the Format Menu, choose "Conditional Formatting..."
Change "Cell Value Is" to "Formula Is"
Enter the formula: =B1<A1*.9
Click the FORMAT button and select your format (Green)
Click the ADD button
Change "Cell Value Is" to "Formula Is"
Enter the formula: =B1<=A1
Set your format (Yellow)
Click the ADD button
Enter the formula: =B1A1
Set your format (Red)
Click OK

These steps are for Excel 2003 or earlier. If you have 2007, then there are
a few differences, but the same idea applies. Post back if you have 2007 and
still need help.

HTH,
Elkar


"Gene Cocchi" wrote:

I am trying to create a "Traffic Light" formula and an experiencing
difficulty. What I am trying to accomplish is if I have a budget # of , say
$3, If the actual cost is less than 90% then Iwant the cell to show green in
color. If the number approaches 90%-100% of the budget # than I want the
cell to show as yellow. And, If the actual nuber exceeds the budget # ($3),
then I want the cell to show up red in color. Has anyone had experience with
this type of situation and if so could you please lend me some pointers?
Thanks in advance.