how to stop a calender count down when a date within the month is met

Hi

I am currently putting a spreadsheet together for a calibration schedule. i have a formula in a cell that counts down the days to a due date. The formula i have used is =if(c4<>0,c4-today(),"due date?"). What i want to is stop the count down in another cell say c5 if the cal is completed with the due date range, but keeps the countdown value in the c4 cell

Any ideas

Cheers
Darren

=if(isblank(c4), "due date?", if(c4>=today(), c4 -today(), "N/A"))

Thank you so much for your help. The formula works a treat

Please close this thread as Solved if everything is good.

Hi i have attached a copy of my sperad sheet i need to stop the count down in cell d4-9 but leave the value when i put a date in cell e4 -9 does anyone have a formula