I have come across many documents explaining the configuration and functionality for Lock-box implementation in SAP. However I have found very little post regarding post processing aspects of Lockbox.
This document is intended to explain the different aspects of post-processing data and assist users to successfully processing the file data. Hence I have excluded lockbox configuration part. This document is applicable only for file processed using BAI2 format
What is Lockbox post processing
Once a lockbox file is processed in SAP system through t-code FLB2 (program RFEBLB00), it is not always necessary that all the checks have successfully posted. Post-processing is required when the lockbox program is not able to automatically clear/apply all available checks in the file.
After the file processing, the the lockbox status will fall under one of following categories:
- Applied: This status is maintained when customer is identified and all the document numbers for that customer are also identified. The program doesn’t check for amount from the file against document/invoice. It means even if amount is overpaid/underpaid in the file, the status will be ‘Applied’.
- Partially Applied: This status is maintained when customer is identified and check has cleared one or more document numbers, but not all documents have been identified/cleared.
- On-Account: It means that customer is identified but no document numbers have been found. Hence, the full amount of check is posted on customer account for further processing with payment advice.
- Unprocessed: This status is maintained when neither customer could be identified through bank information nor document numbers were found, so the check remains in the un-applied payment clearing account for further processing.
How to complete post-processing of lockbox data
This activity is completed using transaction code FLB1 in SAP. Enter the input parameters in the initial screen as shown below and click on 
to process the checks.
In the next screen, we can see the status of all the checks, which were in the file and processed in SAP by lockbox program.
Action required for different Lockbox file status:
1. If the lockbox status is “Applied”, No further processing/action is required for reconciliation. Also, we can not find the payment advice because the system automatically deletes it.
2. If the lockbox status is “Partially Applied”, it requires further action for processing. To process the check, choose the check and then press the post button. After this step, clearing is done via standard SAP process.
3. If the lockbox status is “On-Account”, it requires further action for processing. To process, we need to change the payment advice first (highlighted above). Select the check and then we can insert or delete clearing details. After the changes made, the advice balance should be zero. Save the changes in advice and then post it.
4. If the lockbox status is “Unprocessed”, it requires further action for processing in the same way as that of on-account status. However, we must identify the customer in the payment advice at first before making other changes.
In this way, we can process and post all the checks in SAP system for a lockbox file.