From the support team: Microsoft Dynamics GP Year End Release 2013: General Ledger Year End Close
Microsoft Dynamics GP Year End Release 2013: General Ledger Year End Close – Dynamics GP Support and Services Blog
General Ledger & FinancialsYear-End & 1099
Archived post from 2013. Dynamics GP and the links it points to have changed since; check current documentation before relying on version-specific steps.