I prepare the file to be uploaded with:
Delete columns headings & empty rows.

Save the file as type : CSV (Comma delimited)

Click yes if you have a message : "do you want to keep the workbook in the format?"
Start the transaction ZWFA47A and enter:
Session that must be run with transaction SM35: ZWFAI + company + 3 characters
Controlling area
Version : 0
Document Header Text: Sales force case number
Posting Date & Document date : last day of the month
Select "production" to work with pre-established rates or select "consumption" to work with actual rates.

Error messages must be solved before moving forward |
For instance, if you have the message "Activity type xxx cannot be allocated from cost center xxxx-xxxx" it means that the budget was not entered with KP26.
If no errors found, flag the options:
Execute
A batch input is generated and automatically processed.

A message informs that the session was successfully processed
Go to SM35 to see documents posted