You change a workbook setting:
tools|options|calculation tab|check 1904 date system

Be aware that any date in this workbook will change by 4 years and a day.

And it this can cause trouble when copying dates between two workbooks that have
the opposite settings.



santaviga wrote:

Can anyone advise me if there is a way to calculate negative time in excel.

this is doing my head in, keeps returning ############

Regards

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Dave Peterson