In the California cap-and-trade program, polluting entities use carbon offsets for compliance. Who are they? This tool lets you search for an offset project, user, or facility, and see the linked results. Read more in our original blog post or check out the GitHub repository. This tool was updated as of December 2025.
This tool is designed to make public cap-and-trade data about offset use more easily accessible. It connects the dots between various data sources, and makes it possible to answer questions about how offset projects, regulated entities, and emitting facilities are connected.
Specifically, the underlying data allows us to ask who has used credits from a particular offset project (project → users), which offset projects a particular regulated entity has turned in credits from (user → projects), and which emitting facilities are associated with a regulated entity (user → facilities). Note that while both offset projects and facilities can be connected to a user, the structure of the underlying data does not allow facilities and projects to be directly associated with each other.
Additional information about offset projects can be found in our public offsets database, which includes data on total issuance and retirement, and links out to registry documentation. For our analysis of the overcrediting of forest offset project in particular, as well as a tool for tracking their intersection with wildfire, see our forest offsets tools.
You can cite this work as:
F Chay, J Freeman, D Cullenward (2025) “Compliance users” CarbonPlan doi:10.5281/zenodo.17956162
The California Air Resources Board (CARB) — the regulator in charge of implementing the cap-and-trade program — publishes a variety of cap-and-trade data. This tool connects the dots between three of CARB’s published data sources. Here we describe those sources.
Compliance reports detail how regulated entities comply with their cap-and-trade obligations, including through use of offset credits. We use the compliance reports to associate regulated entities (i.e. users) with offset project IDs and facility IDs. These reports are published at the end of each full compliance period (e.g. 2013-2014, 2015-2017, 2018-2020, 2021-2023), and annually within each compliance period (e.g. 2024).
Mandatory GHG Reporting Data (MRR) are published annually (2013-2024) and provide information on emitting facilities. Some of these emissions are “covered” by cap-and-trade, and therefore form the basis for a compliance obligation. We use the MRR data to connect facility IDs to facility names, types, and locations. A ** next to a facility name indicates a facility that appears in the MRR data, and is listed in the compliance reports, but in a different reporting period.
The Offset Credit Issuance Table provides information about the issuance of offset credits that are eligible for use in the cap-and-trade program. We use the Issuance Table to connect an offset project ID to project names, types, and locations.