There is no problem to change the account number in the vendor or customer
master data, that is :
All Document Items that were created in the old account will be posted in the
same old account when you have a payment posting, compensations, etc.
All document created after the change will be posted in the new account as
well as the payment postings, compensations and others.
The system will separate the postings in accordance with the moment at the
documents were created.
You can do a test in the development client before you do the change in the
For example :-
You can create a new reconciliation account because you want the G/L accounts
to separate out sales. Just switched the setting in Customer Master and off you
go. SAP will recognized the old account for the old postings and used the new
account for any new postings.
Here is the official SAP help on the subject:-
You should run balance sheet adjustment program after any reconciliation
The system performs any adjustments required due to the change of
reconciliation accounts or G/L accounts. The items from the old reconciliation
accounts are allocated to the new accounts.
Since you cannot post to the reconciliation accounts directly, the postings
are made to temporary adjustment accounts.
These adjustment accounts should be displayed along with the relevant
reconciliation account in the balance sheet. The postings are then reversed
after the balance sheet has been created.
The program for sorting the payables and receivables makes the necessary
adjustments automatically. This means that you have to define the adjustment
account numbers and the posting keys for these postings in the system.
If you purchase and install the FI-LC Consolidation application and have
bought up a previous customer or vendor (thus also taking on his/her payables
and receivables), please refer to the note in the report documentation on
changed reconciliation accounts. To define the account numbers, select the
activity Define adjustment accounts for changed reconciliation accounts in the
Accounts Receivable and Accounts Payable Implementation Guide.
You should only run this program if your new reconciliation account is
classified differently from the original in your FS. e.g.. AR to Intercompany
accounts. It will just reclassify the existing balance. The line items will not
be transferred. If not then no need to run the program at all.