Emission sources from your supply chain are called Scope 3 under the Greenhouse Gas Protocol (GHGP). These emissions fall outside of direct company control, but they can influence them or decide via procurement and other policies to choose low carbon options. Some examples of common value chain emission sources include waste produced during operations, purchased goods and services, and business travel.
The upstream and downstream impacts of a business operations are never ending. The GHGP technical guidance for calculating Scope 3 emissions provides 15 categories to consider and a relevant test to decide on where to draw the boundary. If you’re after carbon neutral accreditation you’ll need to seek guidance on applying the relevant test, however if your Scope 3 disclosure is internal the business can decide how to approach it.