Thanks both of you for the reply.

I tried the [ ] formatting on the dates and could not seem to get it working.
For the most part, the subtraction works fine, until I cross over midnight. I have attached a sample, and you can see the errors, where I am having trouble.

I have also highlighted the times that are causing the issue. I tried some simple if statements, but they seem to keep reversing what I want it to do.

(p.s - a few columns look the same, its just different variationsa of what I was trying to do).