How to Quickly Calculate Invoice Due Dates

Calculating invoice due dates in Microsoft® Excel® is easy. If you have struggled to calculate invoice due dates before, your worries are over – in this tip we’ll show you how to do this quickly using the WORKDAY function. The WORKDAY function returns a number that represents a date, before or after a specified number of work days. You can use WORKDAY to exclude weekend or holidays when you calculate invoice due dates or expected delivery times.

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Note: Download the sample workbook to practice this exercise

Applies To: MS Excel 2007,2010 and 2013

1. With reference to the sample workbook; select cell E2.

2. Select the Formulas Tab then Date & Time


3. From the Date & Time function list ; select WORKDAY


4. Then enter C2 as the start date and D2 as Days.


  • Start_date:  A date that represents the start date. (required)
  • Days         : The number of working days before or after start_date. A positive value for days yields a future date; a negative value yields a past date. (required)
  • Holidays   . A list of one or more dates to exclude from the working calendar. The list can be  a range of cells that contain the dates.(optional)

5. Select OK and copy the formula down to cell E8.

6. The value returned by WORKDAY function should be converted to a date as follows.

  • Right click on the value
  • Select Format Cells
  • Select Date under categories
  • Select the Date type
  • Select OK


  • The due date has been returned for each Invoice number
  • The due date excludes weekends  or holidays