1. From the CSV file, highlight the entire column that contains the zip codes. 
  2. Right click on the column and select Format Cells...
  3. On the Number tab select Special
  4. Under Type, select Zip Code
  5. Click Ok
  6. Save and close the CSV File
  7. Import file
Note: It is important that users do not re-open the CSV file after the zip code column has been re-formatted as Excel will automatically revert the changes made and the leading zeros will be dropped.