Info from MS on Microsoft Dynamics GP 2016 R2 and Year-End Update – Version Checks & Upgrades
Microsoft Dynamics GP 2016 R2 and Year-End Update – Version Checks & Upgrades – Microsoft Dynamics GP Community
Payables & ReceivablesYear-End & 1099Install, Upgrade & AdminGP 2016
Archived post from 2016. Dynamics GP and the links it points to have changed since; check current documentation before relying on version-specific steps.