The profile option "GL: Launch AutoReverse After Open Period" to be set as 'Yes' to enable the Auto Reverse journals to be created as soon as the next period is Open.
1) Define the Auto reversal criteria for the required Journal Category from:
select the Category. In R12 you also need to select the Criteria Set associated to the Ledger in the Accounting Setup Manager.
check the AutoReverse button.
select the Reversal Period and Reversal Method to use with the journals of this category.
2) Set the Profile Option GL: Launch Auto Reverse After Open Period to Yes.
3) Enter a journal in GL either manually or import from a sub-ledger or upload through worksheet and post the Journals. Ensure that the period of reversal has never been opened.
4) Open the next period /period of reversal, and thus the trigger is automatically set to reverse the journal in this period.
5) The reversed journal has to be Posted to update the balances.
However, there are a few things that should be kept in mind :
The initial period of the journal entry should be open when opening the period of reversal.
When journal is entered for a particular category, then ensure that the reversal period derived from the journal source has never been opened.
While defining the Auto Reversal criteria the Auto Post reversal button can be checked. So, the journals need not be posted separately and step 5 above can be ignored.