From Collins computing, the 2015 U.S. Payroll Year-End Update has released. Collins has details and more information on changes and deployment.
Collins Dynamics GP Blog: 2015 U.S. Payroll Year-End Update has released
Payroll & HRYear-End & 1099Microsoft & the GP Ecosystem
Archived post from 2015. Dynamics GP and the links it points to have changed since; check current documentation before relying on version-specific steps.