Calculate whether input response is late

I have created a spreadsheet that is being used as a tracking sheet for emergency management purposes. During emergencies this sheet will be shared live with emergency officials to show which incidents are still active and which are waiting for a response, or late for a response.

I have a column with the "Due Time" and I want this to use this cell or entire row to indicate in yellow when the "Due Time" is within 15 minutes of the current time and red when it is past the due time.

Welcome to the forum!

Use conditional formatting. Obviously, you need to use =Now() as part of your formulas. Recall that to get the day fraction of 15 minutes you divide 15 by 1440 (60 minutes per hour times 24 hours per day).

You will need to use a macro like Application.Ontime if you want to force a refresh at periodic intervals. The refresh happens anyway if data is entered and autocalculate is set or F9 is pressed to force a recalculate.