Problem: Fiscal year ends on 12/31 but they want to wait until mid January to close the year. Do they need to change the period end date for period 12 in GL Setup.
Cause: Confusion over impact of period end date.
Resolution: Do not change the period end date. If you need to enter period 01 documents before closing the year, just enter the future period to post. If you have already closed and need to enter transactions for the prior year, just enter the prior period as the period to post. In either case, there is no reason to change the period ending dates in GL Setup.