Example: Cell A2 contains the date 6/1/22. I want Cell B2 to be highlighted red if nothing is entered in to cell B2 after 30 days. How do I do it?

This could be your formula for cell B" with Conditional Formatting with red fill:

=IF(AND(B2=""),TODAY()-A2>30)

That worked! Thanks a lot I really appreciate it!

To take it one step further: Cells A2:A6 contain dates. Cells C2:C6 have letter grades (A, B, or C) I want Cells B2:B6 to be highlighted red if nothing is entered in to those cells after 30 days if they're an A, or 15 days if they're a B, or 7 days if they're a C. How do I do that?

See if I got it right:

=OR(AND(C2="A",TODAY()-A2>30),AND(C2="B",TODAY()-A2>15),AND(C2="C",TODAY()-A2>7))

Unfortunately that did not work.

Saying "did not work" isn't very constructive. You probably got something messed up in your Conditional Formatting.
Attached you will find my testing. Have a try changing grades in column C.
"A" already is done, now enter "B" in cell C2 and pull down and see the difference and finally do the same with "C".

Attached Files

Test_CF_forum.xlsx (11.1 KB, 6 views)

You're right, I apologize for my vagueness. I see how it works on your example sheet but I cannot duplicate the efforts on my own. I can copy and paste your formula to do exactly what you did but when I try to apply it elsewhere by changing just the simple data I fail. Please see attached sheet.

I am trying to get column J to fill red when a date is not entered 30 days after column I if it has a 1 in column C, 15 days if it has a 2 in column C, and 7 days if it has a 3 in column C. Please see my conditional formatting to see where I am messing it up.

Attached Files

Copy of CRG Cancellation & PIF Releases Tracking.xlsx (375.4 KB, 5 views)

So where you messed up was in post #4 where you asked about the grades "ABC" which is text. In column C you have numbers 123 so the formula in CF cannot be C6="1" but must be C6=1 .
If you use double quotation marks it goes without saying that you are dealing with text and as you well know in Excel "1" (text format) is not equal to 1 (decimal format).
I leave you the task of fixing the whole formula .

PS. forgot about when J6 has a date, does it still need be highlighted if over date ?
If so then the formula in CF could be:

=AND(J6="",OR(AND(C6=1,TODAY()-I6>30),AND(C6=2,TODAY()-I6>15),AND(C6=3,TODAY()-I6>7)))

That worked! That was my issue was putting the numbers in "" instead of excluding. Once a date is entered I want the red fill to disappear which your formula does, so I am officially a go! Thank you so much for your patience and help!

Thanks for the positive feedback, glad having been of some help.