I think there is a way around the time subtraction issue I have in Excel. The problem is that when the time in cell F (for example 11:29am) is less than the one in cell A (for example 11:30am), the final time subtraction is displaying 59 minutes instead of -1 min(s). The -1 minute is indicating that the whole task was completed 1 minute ahead of the projected time. I am aware that Excel cannot display negative times; instead of Excel displaying negative times in my situation, I would like Excel to still display 1.

Here is the formula I used

```
=IF(AND(A3="",E3=""),"",IF(OR(A3="",E3=""),"",MOD(E3-A3,1))).
```

The formula for the time format conversion from mm: s to mm is

```
=IF (ISERROR (HOUR (F3)*60+MINUTE (F3)),"", HOUR (F3)*60+MINUTE (F3))
```

I need improvement to the `IF(AND(A3="",E3=""),"",IF(OR(A3="",E3=""),"",MOD(E3-A3,1)))`

to display a negative/positive time.

Note: A sample copy of the data is attached. The incorrect times are highlighted in YELLOW color.

`IF(AND(A3="",E3=""),"", ... )`

. If both of the cells are blank, then either of them are, by definition. Since both branches lead to the same result (`""`

), it makes no difference if you just catch blanks in the 'OR' statement. – mcalex Apr 22 '13 at 13:59