What Companies Need to Know About California SB 253 - Reporting, Deadlines, and How to Prepare

California SB 253 is shaping how large companies measure, verify, and publicly disclose their greenhouse gas emissions. If your company earns more than $1B in annual revenue and does business in California, you will be required to publicly report Scope 1 and Scope 2 emissions by June 2026, followed by Scope 3 emissions in 2027.

This marks a major shift in U.S. climate reporting. Disclosures are now regulated, assured, and expected to meet similar standards as financial data. Companies that establish the right systems in 2026 will have the smoothest path through the first reporting cycle.

Planet FWD is supporting Sustainability, ESG, Regulatory Affairs and Compliance teams preparing for SB 253. Here’s what to know and what to do now.

Who SB 253 Applies To

SB 253 covers any company with:
• More than $1B in annual revenue, and
• Business operations in California

Most large, multi-entity, multi-facility companies will fall in scope.

SB 253 Reporting Deadlines

2026
• Public reporting of Scope 1 and Scope 2 emissions for FY 2025
• Limited assurance (third-party verification) begins

2027
• Public reporting of Scope 3 emissions for FY 2026
• Ongoing reporting of Scope 1 and 2
• Continued limited assurance

2030
• Reasonable assurance required for Scope 1 and 2
• Assurance for Scope 3 begins

If you want a low-stress 2026, your FY 2025 data collection needs to be structured and audit-ready well before spring.

What Makes SB 253 Different

Many companies believe their current carbon accounting process is sufficient. SB 253 raises the bar. The law requires a level of granularity, data quality, and documentation that typical sustainability dashboards and internal spreadsheets don’t provide.

Required Scope 1 Breakouts

Your provider must support reporting across:
• Stationary combustion
• Mobile combustion
• Process emissions
• Fugitive emissions
• Biogenic emissions
• Agricultural sources (if applicable)
• Optional gas-by-gas detail (CO₂, CH₄, N₂O, HFCs, etc.)

Required Scope 2 Breakouts

SB 253 requires:
• Location-based electricity
• Market-based electricity
• Purchased steam, heating, and cooling (location- and market-based)

District energy systems, central plants, or landlord-managed utilities must be accounted for — a gap in many tools.

Boundary + Reporting Requirements

Your carbon accounting system must also handle:
• Organizational boundaries (equity share, financial or operational control)
• Operational boundaries with explicit inclusions/exclusions
• De minimis thresholds with clear rationale
• Audit trails, documentation, and evidence for each emission source
• Output formats aligned to CARB’s public disclosure templates

If your team is relying on manual workarounds, you will face issues during assurance.

Why Third-Party Assurance Matters Now

Limited assurance starts in 2026. That means companies need:
• A carbon inventory aligned with the Greenhouse Gas Protocol
• Clean documentation for every emission source
• Version control and data safeguards that stand up to verifier review
• A provider whose methodology has already been examined by assurance firms

Planet FWD has an assurance partnership designed for SB 253, offering faster verification and discounted rates. Our exports include the evidence and data trails required for limited assurance.

Questions to Ask Your Provider

These questions reveal immediately whether a platform is ready for SB 253:

Assurance

• Can you produce audit trails that meet internal-control standards?
• Do you support limited assurance today?
• Has an independent verifier reviewed your methodology?

Scope 3 Readiness

• Can your system collect primary supplier data at scale?
• How much of your customers’ Scope 3 data is based on primary vs. secondary inputs?

California Compliance

• Are you tracking CARB updates and rulemaking?
• Do your exports align with CARB’s disclosure templates?

Data Quality

• How do you prevent user-input errors?
• How do you handle missing or incomplete data in a compliant way?

How Planet FWD Supports SB 253 Compliance

Planet FWD is designed for the reporting rigor SB 253 demands. We work with companies that will be among the first required to disclose.

1. Structured, guided data collection

We walk teams through the exact inputs required for FY 2025, including complex sources like purchased steam and fugitive emissions.

2. Audit-ready methodology

Our accounting framework aligns with the GHG Protocol and produces documentation built for verifier review.

3. Assurance-ready exports

Each export includes evidence, controls, and source-level data trails needed for limited assurance.

4. Direct auditor partnerships

Customers can access discounted assurance packages through our independent partner network.

5. Automatic CARB-aligned reporting

As CARB finalizes requirements, Planet FWD’s outputs update accordingly.

6. Integrated Scope 1, 2, and 3

Scope 3 becomes mandatory in 2027. Our platform includes supplier engagement tools and detailed data models that make Scope 3 manageable.

Why Starting Now Matters

If your fiscal year ends December 2025, you are already in the reporting period that will be disclosed in 2026. Delays in establishing your system create three issues:

Lower data quality — Retroactive collection is harder to verify.
Assurance bottlenecks — Verifiers might reach capacity early in 2026.
Compressed timelines — Companies will need a complete Scope 1 and 2 inventory early in 2026 to meet the June deadline.

Teams that start now will complete reporting smoothly and avoid unnecessary verification costs.

Need Support?

Planet FWD can complete an SB 253 readiness assessment in 30 minutes. If you want clarity on whether your company is in scope, what gaps you need to close, and how to build an audit-ready inventory before deadlines hit, our team can walk you through next steps.

Reach out anytime to get started at hello@planetfwd.com