Explanation
In Excel, dates are simply serial numbers.
This means that January 1, 2050 is the serial number 54,789.
Calculate expiration date
To calculate an expiration in the future, you can use a variety of formulas. In the example shown, the formulas used in column D are: =B5+30 // 30 days =B5+90 // 90 days =EOMONTH(B7,0) // end of month =EDATE(B8,1) // next month =EOMONTH(B7,0)+1 // 1st of next month =EDATE(B10,12) // 1 year
