Publication 5165, Guide for Electronically Filing Affordable Care Act (ACA) Information Returns (AIR) for Software Developers and Transmitters (Processing Year [PY] 2017), outlines the communication procedures, transmission formats, business rules and validation procedures for information returns transmitted electronically through the AIR System.
Beginning with Tax Year 2016 submissions, error files returned to Transmitters will show exactly which business rules were violated by the transmission rather than displaying which error codes were triggered. These rules will have a one-to-one relationship to the rules posted on the AIR Program page. The change is designed to help Transmitters better understand the exact nature of the business rule violation.
You can download Publication 5165 below, or view the publication via irs.gov.