California’s SB 253 will require large companies doing business in the state to disclose their greenhouse gas (GHG) emissions across Scope 1, Scope 2, and Scope 3, following the Greenhouse Gas Protocol. Even with litigation and timing questions, mid‑market teams should start now by confirming if the law applies, building a first GHG inventory, mapping data owners, and creating an audit‑ready process. Greenplaces’ hybrid AI + human-expert model helps companies move from “where do we start?” to defensible, framework-aligned reporting.
If sustainability responsibilities were added to your job description on top of everything else, you are not alone. Many people responsible for SB 253 preparation come from operations, HR, finance, or marketing — not from a climate background.
At the same time, California’s climate laws feel urgent and confusing. The California Air Resources Board (CARB) approved regulations for SB 253 and SB 261 on February 26, 2026, but parts of the package face legal challenges and changing timelines. It can be hard to tell what actually matters this year versus “someday.”
This guide breaks SB 253 preparation into seven clear steps you can tackle with a small team. The goal: give you a realistic starting point, an audit‑ready path forward, and a way to show leadership that you are on top of it, without needing to become a climate lawyer.
SB 253 BASICS
What is SB 253 actually asking you to do?
SB 253, the Climate Corporate Data Accountability Act, requires large companies that do business in California to measure and disclose their greenhouse gas emissions across three “scopes” following the GHG Protocol. Scope 1 covers direct emissions from your own operations (like onsite fuel use). Scope 2 covers emissions from purchased electricity and energy. Scope 3 covers everything in your value chain, such as purchased goods, business travel, and upstream and downstream logistics.
California estimates that thousands of public and private companies will ultimately fall under SB 253. CARB’s regulations require Scope 1 and 2 reporting first, followed by Scope 3, with data prepared in line with GHG Protocol standards. Even though litigation is ongoing, experts expect some form of climate disclosure to move ahead, meaning that early work on your emissions data will not be wasted.
If you need a deeper legal and regulatory overview, Greenplaces maintains a dedicated SB 253 regulation explainer with updated requirements and key dates.
STEP 1: CHECK APPLICABILITY
How do you figure out if SB 253 applies to your company?
The first step is to confirm whether your company is in scope for SB 253 based on revenue and doing business in California. The law applies to U.S. entities with over $1 billion in annual revenue that “do business” in California, a term linked to California tax code definitions — for example, thresholds for sales, property, or payroll in the state. If your company is part of a larger corporate group, you may need help from tax and legal teams to interpret which entities are counted.
Because SB 253 sits alongside SB 261 (climate-related financial risk reporting for companies with over $500 million in revenue), many businesses will need to consider both laws at once. SB 261 enforcement is currently paused by an injunction while litigation proceeds, but SB 253 is moving ahead. That means carbon accounting work you do now will likely support both emissions disclosure and future climate-risk reporting.
For an accessible overview of both laws, you can refer to Greenplaces’ guide to California’s climate accountability package, which explains SB 253 and SB 261 side by side.
STEP 2: MAP YOUR “EMISSIONS DATA OWNERS”
Who inside the business actually holds the data you’ll need?
Once you know SB 253 is likely to apply, the most practical next step is mapping out where key data lives and who owns it. You are essentially building a contact list and system list for your future GHG inventory. For most mid‑market companies, this means engaging finance, facilities/real estate, procurement, IT, and HR.
For example:
- Utility and fuel bills usually sit with facilities, operations, or accounts payable.
- Travel data may come from your travel management company, expense system, or HR.
- Purchased goods and services data likely sits in ERP or procurement tools.
This “data owner map” does not require any complex modeling. It’s a spreadsheet with columns for data type, system, owner, and level of completeness. Studies show that data quality and governance are top barriers to climate reporting readiness for mid‑sized companies. Getting clarity on data owners now will save significant time when you begin detailed carbon accounting.
Greenplaces’ mid-market sustainability platform is designed around these data owners, using a hybrid AI + expert approach to pull information from finance and operations systems into a single, audit‑ready emissions dataset.
STEP 3: BUILD YOUR FIRST GHG INVENTORY
What does a “good enough” first carbon footprint look like?
You do not need a perfect model on day one. A “good enough” first greenhouse gas (GHG) inventory starts with clear boundaries and the major emission sources, using the Greenhouse Gas Protocol. Many companies start with:
- Scope 1: Onsite fuel use (natural gas, diesel, propane) and company vehicles.
- Scope 2: Purchased electricity and other energy.
- Priority Scope 3 categories, such as purchased goods and services, business travel, and employee commuting.
SB 253 expects reporting to align with GHG Protocol, which is already the basis for most global reporting frameworks and voluntary initiatives.^4 Building your inventory to that standard now will support future CDP, SBTi, and ISSB/SASB reporting. CDP, for example, requires detailed Scope 1–3 data and is used by investors representing over $127 trillion in assets.
Greenplaces offers carbon accounting services across Scopes 1, 2, and 3 that combine data automation with human review, so you can move from raw bills and spreadsheets to a defensible emissions baseline that aligns with SB 253 expectations.
STEP 4: FOCUS ON MATERIAL SCOPE 3 CATEGORIES
How do you avoid getting lost in every possible Scope 3 emission?
Scope 3, the emissions from your value chain and vendors, is where SB 253 preparation can feel overwhelming. The key is to focus on the categories that are likely to be largest and most material for your business model. For many mid‑market companies, purchased goods and services, capital goods, upstream transport and distribution, and business travel make up the bulk of Scope 3 emissions.
A practical approach is to:
- Use spend-based methods as a first pass where activity data is not yet available.
- Prioritize higher-impact vendors and categories for better data over time.
- Document methods and assumptions carefully for audit and assurance.
California’s rules anticipate independent assurance for reported emissions, particularly over time as requirements phase in. That means your documentation, even for early, high-level estimates, matters. Greenplaces’ hybrid AI + expert model helps teams refine Scope 3 data each year instead of trying to do everything perfectly in year one.
STEP 5: SET GOVERNANCE, NOT JUST A PROJECT PLAN
How do you turn SB 253 from a one-off scramble into a repeatable process?
Treat SB 253 like any other recurring reporting requirement, not a one‑time project. That means creating simple governance: who is accountable, which teams provide data, and how often the information is reviewed. Many companies are starting to integrate climate reporting into existing risk and reporting structures built for financial audits and SOC 2.
Practical moves include:
- Naming an executive sponsor (often finance or legal).
- Creating a cross-functional working group with clear roles.
- Aligning your reporting timetable with financial close or annual reporting cycles.
Regulators and investors are increasingly focused on internal controls over sustainability reporting, mirroring internal controls over financial reporting. Even lightweight controls, documented reviews, version control, and clear sign‑offs, will help you be “assurance ready” when SB 253 assurance requirements fully take effect.
Greenplaces supports this by providing one platform that centralizes data, methodologies, and evidence trails, making it easier to show auditors and stakeholders how emissions numbers were produced.
STEP 6: CHOOSE AN OPERATING MODEL (AND PARTNERS)
Do you need software, consultants, or both to handle SB 253?
Most mid‑market teams do not have the time or in‑house expertise to build a full SB 253 program from scratch. At the same time, they may not be ready for a large, open‑ended consulting engagement. An effective operating model blends internal ownership with outside support where it adds the most value.
Common elements include:
- A platform to centralize emissions data, automate calculations, and store evidence.
- Access to human experts who know SB 253, GHG Protocol, and related frameworks (CDP, SBTi, ISSB/SASB, GRI).
- Clear scopes of work so you know what stays in‑house vs. what is handled by partners.
Surveys show that more than half of companies plan to increase investment in climate and ESG reporting tools to keep up with new disclosure rules and investor expectations. Greenplaces was built for this mid‑market reality: a mid-market sustainability platform powered by a hybrid AI + expert model that replaces a patchwork of point tools with one place to manage carbon accounting and California climate compliance.
STEP 7: CONNECT SB 253 WORK TO YOUR BROADER STRATEGY
How does SB 253 prep help with CDP, climate risk, and RFPs?
While SB 253 may feel like another compliance box, the data and processes you build can support several other priorities. The same GHG inventory can underpin CDP disclosures, ISSB/SASB-aligned reporting, customer questionnaires, and climate-risk analysis for SB 261 or TCFD/IFRS S2-style reporting.
For example:
- CDP’s climate questionnaire requires detailed Scope 1–3 emissions and climate-risk information, and over 22,000 companies now report through CDP.
- Investors and large customers increasingly request climate data from suppliers, using it in procurement and risk decisions.
- California’s SB 261 requires climate-related financial risk reporting aligned with TCFD or equivalent frameworks, though enforcement timing is still in flux due to litigation.
By treating SB 253 preparation as the foundation for broader sustainability and risk reporting, you create more value from the same work. Greenplaces ties SB 253 support to services across CDP, ISSB and SASB, and climate-risk analysis, so your emissions data serves multiple business needs, from regulatory compliance to winning RFPs.
What to do next
If SB 253 feels intimidating, start with the basics: confirm whether the law likely applies to your company, list out your data owners and systems, and set a realistic plan for your first GHG inventory. From there, prioritize the most material Scope 3 categories and build simple, repeatable governance so this work becomes part of business as usual, not an annual fire drill.
As you make progress, connect SB 253 preparation to other goals: better CDP scores, stronger climate-risk disclosures, and clearer answers for customers asking climate questions in RFPs. When you’re ready for support, Greenplaces can help you build an audit‑ready GHG inventory, align with SB 253 expectations, and integrate your emissions data into broader frameworks like CDP and ISSB/SASB — all with a hybrid AI + human-expert approach designed for mid‑market teams.
If you need a place to start this week, use the SB 253 starter checklist to anchor conversations with finance, legal, and operations and to show leadership that you have a clear, defensible plan.
