Thanks for explaining, can you suggest an alternative formula that wouldn't return a #VALUE! error then?The first part of the formula evaluates to blank.
The second part of the formula is is subtracting given time from blank which leads to negative value.
Function Time does not support negative values, hence error.
=IFERROR(IF(ISBLANK(B14),"",C14-B14)-TIME(0,30,0),"")
=IF(ISBLANK(B14),"",C14-B14-TIME(0,30,0))
Or just move the paranthesis that would basically mean:
If cell is blank then return blank, else subtract C14 from B14 and subtract 30 mins:
Excel Formula:=IF(ISBLANK(B14),"",C14-B14-TIME(0,30,0))