What's inside

Everything you need to get compliant — organized in the right order

SB 253 enforcement starts in 2026 for Scope 1 and 2. Scope 3 disclosures are due by 2027. This checklist walks you through every step, from entity boundary decisions to board-level reporting cadence.

Scope 1, 2, and 3 mapping framework — exactly what to document for each scope, with emission factor database recommendations
Entity boundary decision guide — operational control vs. financial control vs. equity share, with clarity on which applies to your structure
Third-party assurance timeline — when to engage your assurance provider and what limited vs. reasonable assurance actually requires
Board reporting and governance checklist — what internal controls and executive sign-offs CARB expects before your first disclosure

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SB 253 Compliance Checklist — 10 Steps

How to use this checklist: Work through steps in order — each builds on the previous. Start with Steps 1–2 (entity scope) before mapping emissions. Engage your assurance provider (Step 9) at least 6 months before your first disclosure deadline.

Legal / Applicability

Determine if your company meets the $1B revenue threshold

SB 253 applies to any entity that "does business in California" with total annual revenues exceeding $1 billion USD. This includes US subsidiaries of foreign multinationals. Confirm your California business nexus (employees, customers, facilities, or contracts in CA), your total consolidated revenues, and which legal entity is the "reporting entity" under CARB rules. Document your applicability determination — CARB may request it.

Entity Structure

Identify your reporting entity boundaries

Under GHG Protocol, you must choose an organizational boundary approach: Operational Control (report where you have operational authority), Financial Control (report where you have financial authority), or Equity Share (report proportional to ownership stake). Most companies use Operational Control. Document your choice and apply it consistently. Joint ventures, subsidiaries, and acquired entities need explicit boundary treatment.

Scope 1

Map Scope 1 emission sources (direct combustion, fleet, refrigerants)

Scope 1 covers all direct emissions within your operational boundary. Inventory: stationary combustion (boilers, furnaces, generators), mobile combustion (company vehicles, aircraft), process emissions (manufacturing, chemical production), and fugitive emissions (refrigerant leaks, SF6). For each source, identify the fuel type, activity data source (utility bills, fuel receipts, equipment logs), and applicable emission factor from EPA's GHG Emission Factors Hub (2024).

Scope 2

Map Scope 2 sources (purchased electricity, heating, cooling)

Scope 2 covers purchased energy: electricity, steam, heat, and cooling. SB 253 requires both location-based (eGRID factors) and market-based (supplier-specific or residual mix) accounting. Collect 12 months of utility bills per facility. If you have renewable energy contracts (PPAs, RECs), document them for market-based calculation. Map each facility to its grid region using EPA eGRID subregion data.

Scope 3

Begin Scope 3 materiality assessment (15 categories)

GHG Protocol defines 15 Scope 3 categories. SB 253 requires you to assess materiality across all of them. High-materiality categories for most companies: Cat. 1 (purchased goods & services), Cat. 3 (fuel & energy activities), Cat. 4 (upstream transportation), Cat. 6 (business travel), Cat. 7 (employee commuting), Cat. 11 (use of sold products), Cat. 15 (investments). A category is material if it represents ≥1% of total estimated Scope 3 or is relevant to stakeholders. Document your screening methodology.

Methodology

Select emission factor databases (EPA, DEFRA, ecoinvent)

Choose your emission factor sources by scope and geography: EPA GHG Emission Factors Hub (US Scope 1 & 2, updated annually), DEFRA UK Government GHG Conversion Factors (UK and international travel), ecoinvent database (process-level Scope 3, supply chain LCA), EXIOBASE / USEEIO (spend-based Scope 3 for procurement). Document the version and date of each database used — SB 253 assurance requires consistent factor documentation across reporting periods.

Governance

Establish data collection processes across business units

Emissions data lives across procurement, facilities, HR, finance, and logistics. Assign a data owner per business unit, define the data they're responsible for (e.g., Facilities → utility bills, Fleet → fuel receipts, HR → headcount and commute survey), set collection frequency (quarterly or annual), and build a data submission workflow. Establish data quality controls: verification steps, approval chains, and audit trails. This infrastructure is what your assurance provider will review.

Methodology

Set baseline year and choose calculation methodology

Your baseline year is the reference point for all future emissions targets and performance tracking. Choose the most recent complete fiscal year with reliable data. Document your recalculation policy — SB 253 requires recalculation if structural changes (M&A, divestitures) make the baseline unrepresentative. Confirm GHG Protocol Corporate Standard alignment throughout. Your methodology document should cover: boundary approach, emission factor sources, activity data collection methods, and uncertainty assessment.

Assurance

Engage third-party assurance provider (limited assurance Year 1)

SB 253 requires limited assurance for Scope 1 and 2 starting with the first disclosure (FY2025 data, due 2026). Reasonable assurance for Scope 1 & 2 is phased in by 2030; Scope 3 limited assurance by 2030. Qualified assurance providers include: accredited accounting firms (Big 4 and mid-market), environmental consulting firms with ISO 14064-3 credentials, and registered verification bodies. Start this process 6–9 months early — demand is high. Provide your assurance provider with your methodology document, data collection evidence, and boundary determination before engagement begins.

Governance

Build internal review and board-level reporting cadence

CARB expects robust internal controls over your emissions disclosure — similar to financial reporting. Establish: a cross-functional climate disclosure committee (Legal, Finance, Operations, Sustainability), a board-level review and approval process before disclosure publication, an internal audit trail for all data inputs and assumptions, and an annual reporting calendar aligned with CARB's submission deadlines. Assign a named executive (CSO, CFO, or General Counsel) as disclosure owner. Document the oversight structure in your emissions report.

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Key SB 253 Deadlines

Scope 1 & 2 first disclosure: FY2025 data due in 2026 · Scope 3 first disclosure: FY2026 data due in 2027 · Limited assurance: required from Year 1 · Penalty exposure: up to $500K/year for non-disclosure

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SB 253 Compliance Checklist —10 Steps Before the 2027 Deadline

Everything you need to get compliant — organized in the right order

Download Your SB 253 Compliance Checklist

SB 253 Compliance Checklist — 10 Steps

Key SB 253 Deadlines

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Related Resources

SB 253 Compliance Checklist —
10 Steps Before the 2027 Deadline