SAP Message 9P018 - Separation not possible; input VAT already separated for this period

Diagnosis
You want to separate input VAT for incoming invoices included in theUNDF tax grouping version. This is, however, not possible because theprogram for input VAT separation has already been run, and there is datastored in the database.

Procedure
To delete the separation entries in the database, choose ClearProcessed Invoices .
Note: You can only delete these entries if the system has not alreadylinked export invoices to incoming invoices assigned to the exportoperation type during the last VAT separation. If linking has alreadytaken place, you have to delete the entries from the database first asfollows:
In the SAP Easy Access Menu, choose Accounting -> FinancialAccounting -> General Ledger -> Reporting -> TaxReports -> Russia -> Separate VAT Accounting ->Link Eport Invoices.
Choose Clear Processed Invoices .