If you're working with negative time, you have the base date set to 1904.

Tools|options|Calculation tab.
(else negative times/dates will appear as ###########'s.)

But you could use:
=-TIME(3,12,30)
to get
-3:12:30



L_n_da wrote:

I have document with time in format [h]:mm. Mostly people want to add units
of time but occasionally they need to enter negative value. Putting minus
sign in front of value or brackets does not work. What can we do?

--

Dave Peterson