This issue is generally due to Excel's auto-formatting hiding the actual data behind the scenes, and displaying its formatted version of the data. What normally happens is that the field has a 4 digit value in the zip code field, but the field is formatted as Zip Code, so it looks like the leading 0 is there when it is not. SHIPSTORE takes the raw data from the file when importing, not the formatted version that Excel is displaying, so because the data itself does not have the leading 0, SS will not import it that way.

To fix this issue, follow the steps below:

  1.  Open your excel file, and add a column to the right of the zip code column
  2.  In the first cell in that new column, type in the following formula, where {zip code field here} is the cell   to the left of this field:
    =CONCATENATE(REPT("0", 5-len({zip code field here})), {zip code field here})
  3.  Select the cell from step 2, then scroll to the bottom of the list and hold Shift and click the last cell in   this column. Click the Fill --> Down option on the top bar. This should copy this formula to all rows in   this column.
  4.  Insert a column to the right of the one you created in step 1, and format it as Text
  5.  Click on the first cell in the column you created in step 1, and press Ctrl+Shift+Down Arrow on your   keyboard. This should select all cells in this column
  6.  Copy (Ctrl+C)the selection, then with your cursor in the first cell of the column created in step 4, right-   click and select Values under the "Paste Options" section. This will copy the data as is.
  7.  Delete your original zip code column, as well as the column created in step 1