Comparing dates in two columns with matching criteria - excel

Question

I'm trying to fill out a sheet with a somewhat complicated criteria, I have four columns I'm interested in, however the columns are mixed into a much larger table, sorry vlookup :(
There are two columns that contain an ID# and a Category, one column with date and time stamp, and one that MAY contain a date and time stamp. (Column1,2,3,4 respectively)
Column 3 is when an action took place, Column 4 is the next time that action with the same ID# and Category has to have been completed by.
Essentially I need a cell(s) that will check for a date in Column 4, if there is one, find the next value in Column 3 that is greater than that of column 3 in the row with the value in Column 4, AND has the same ID, AND Category and compare them to see if it was done on time, preferably also by how much if it was late.
I'm able to find it almost with:
{=MAX(IF([#[Column 2]]=[Column 2],[Column 4]))}
Entered as an array formula, however that will only give me the last time that Category was given a "Next Due Date" and similarly with Column 1 replaced for Column 2 in the code sample above, I only get the last time that ID# was given a "Next Due Date".
As some Event ID# can be around for many days, and can run concurrently with others there's no guarantee all IDs will be grouped, nor Categories within those IDs.
It appears any attempts to add an AND(.. function break the array, though I'm not positive I'm not just messing up the placement of it.
It's perfectly fine if the solution involves creating helper cells.
The table is sorted chronologically by column 3 with the latest date at the top if that's any help.
TYVM for even taking the time to read this :)
Edit 1:
Sample Data
I've included an image with some sample data, to clarify the awkward sentence above. The orange arrows are pointing to two dates that would be compared and the event was late. the Green points to a group that was on time.
the categories are
Those two are being compared because each set has the same category, and ID. I hope that clears it up :)

Answer 1

You could try this formula (goes into column E):
=IFERROR( IF($D2<>"", LOOKUP(2,1/($F1:$F$2=$F2),$C1:$C$2), ""), "")
Very important here are the $ signs, as the searched area is supposed to move with the row. (Note: this formula goes into E2. You then copy > pastespecial (only Formulas) it into the rest of the column.)
My table looks like this:
A B C D E F
ID Category Start-date Due-Date Completion-Date ID+Cat. (Helper column)
The formula in F is simply =$A2 & $B2. The data starts in Row 2.
You will need to replace the columns with yours.
Please let me know if this is what you were looking for.