1900 and 1904 Date Formatting
Excel and some database systems are capable of using both 1900 and 1904 date systems. In the 1900 date system, which Excel uses by default, the earliest possible date is January 1, 1900. In the 1904 system the earliest possible date is January 1, 1904. The latter system was devised to deal with problems caused by the fact that 1900 is not a leap year.
Anyone who has used Excel fairly often will realize that a date can be converted to a number. So if we enter 7/4/1976 in a cell and the just past the text of this entry in an adjacent cell, we get the number 27945.
In Excel 2016, if you create a new workbook and then go to File . . . Options . . .Advanced, and scroll down to the 'When calculating this workbook' you'll see the option 'Use 1904 date system'.
If you check off this option and then enter 7/4/1976 in the new workbook and copy the text only to an adjacent cells, you get the number 26483.
The difference between these two numbers and any two dates entered with the two systems is 1462. This is something to keep in mind as dates may get converted to numeric form when text is exported from spreadsheets and other systems. If you're finding that the dates in metadata for documents are inaccurate consider this possible source of the problem.