The ISCC PLUS system is built upon a set of obligatory basic requirements. These are amongst others the requirements on sustainability of the production area (ISCC PLUS 202) and the requirements on the chain of custody (traceability: ISCC PLUS 203; mass balance: ISCC PLUS 204-01, physical separation: ISCC PLUS 204-02). Additionally, there are voluntary add-ons that exceed the obligatory sustainability requirements. Companies can choose these add-ons as voluntary additional modules in order to prove compliance to a specific matter, e.g. specific biodiversity measures or a low greenhouse gas emission.
For farmers, fist gathering points and conversion units, that have already been certified under ISCC DE or ISCC EU, ISCC PLUS offers the possibility to extend their existing sustainability certification under ISCC DE or ISCC EU to other scopes of application (e.g. oil seed meal, DDGS, oil for food products and other applications). ISCC PLUS accepts ISCC EU as well as ISCC DE. Other certification schemes are not accepted under ISCC PLUS so far. Companies certified under ISCC PLUS must assure that the upstream chain of custody (up to the production area) has been certified solely under ISCC. In addition companies have to extend the scope of the quantity bookkeeping to the new sustainability attributes (add-ons).
You can find all valid ISCC PLUS system documents here.