Sheldon from Etelligent Solutions has collected a number of great resources on Year End Close for Dynamics GP.
He’s also a fan of MyGPSearch.com and just a really nice guy.
Dynamics GP Year End Close Resources – Etelligent Solutions
General Ledger & FinancialsYear-End & 1099
Archived post from 2011. Dynamics GP and the links it points to have changed since; check current documentation before relying on version-specific steps.