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v1.4.3Last reviewed November 2026

California SB-253 (Climate Corporate Data Accountability Act)

California SB-253 methodology — two scopes, two deadlines. Scope 1 and 2 were first reported by 10 November 2026 on the GHG Protocol Corporate Standard, with no assurance in year one; Scope 3 follows from 2027, within 180 days of Scope 1 and 2, with a good-faith safe harbor to 2030. Applies at 1 billion dollars total revenue, roughly 5,000 to 6,000 entities, with penalties up to 500,000 dollars per year.
MasterBrain v2026.284 · updated 6 Nov 2026

California’s SB-253 is the most consequential US climate-disclosure obligation now in force. It requires companies doing business in California with over $1 billion in total annual revenue to publicly report Scope 1, 2, and 3 emissions — and unlike the stalled federal rule, it is live, with a CARB-set deadline weeks away.

Its revenue test is measured on total company revenue, not California revenue, so a private multinational headquartered in another state can be fully in scope. This is a national obligation wearing a state-law label.

Quick Answer

SB-253 requires entities with over $1bn total annual revenue doing business in California to report Scope 1 and 2 by 10 November 2026 and Scope 3 from 2027, on the GHG Protocol. Assurance phases in toward reasonable by 2030.

US / California Disclosure · 16 min read

Step-by-step method for meeting California SB-253: the Reporting Entity test (the $1 billion total-revenue threshold and the “doing business in California” reach), what to report and when (Scope 1 and 2 by 10 November 2026, Scope 3 from 2027 with a 180-day statutory lag), calculation on the GHG Protocol, the assurance ramp toward reasonable assurance by 2030, the $500,000 penalty and the Scope 3 good-faith safe harbor, and how SB-253 differs from its sibling SB-261. Framework: Climate Corporate Data Accountability Act (SB-253, 2023) as amended by SB-219 (2024), Health & Safety Code §38532, and the CARB initial implementing regulation adopted 26 February 2026.

10 Nov 2026
First Scope 1 & 2 report was due (deadline passed) CARB-set deadline for the inaugural Scope 1 and Scope 2 disclosure, covering data for fiscal years ending in 2025. No third-party assurance required for this first cycle. Scope 3 follows from 2027.
Status (11 November 2026): in force, first deadline passed — SB-253 is not enjoined

SB-253 is in force. The California Air Resources Board (CARB) approved the initial implementing regulation by unanimous vote on 26 February 2026; the revised version took effect on 12 October 2026, and the first Scope 1 and Scope 2 reports were due 10 November 2026. CARB had announced no extension or new enforcement notice by 11 November 2026. This is the critical distinction from both the stayed federal SEC rule and from SB-253’s own sibling: the Ninth Circuit injunction of November 2025 applies only to SB-261 (the climate-risk law), leaving its enforcement paused. SB-253 was not enjoined — covered companies should have filed their first Scope 1 and 2 reports, and a company that did not should file as soon as it can. A second CARB rulemaking is expected to set post-2026 dates, format, and assurance detail; verify the current position with CARB before relying on any specific later-year date.

A methodology page is the execution layer — it takes the emissions concepts from the glossary, the disclosure rule from the standard, and the GHG Protocol calculation basis, and tells you exactly how to determine whether you are in scope, build the inventory, and file by the deadline. If you already know you are a Reporting Entity, jump to what to report and when or the worked examples.

2023
EnactedClimate Corporate Data Accountability Act (SB-253) signed into law, alongside the Climate-Related Financial Risk Act (SB-261).
Oct 2024
Amended by SB-219SB-219 moved the CARB rulemaking deadline to 1 July 2025, adjusted fee timing, and gave CARB discretion over the Scope 3 reporting schedule. The laws are still called SB-253 and SB-261; codified at Health & Safety Code §38532.
Nov 2025
Ninth Circuit injunction — SB-261 onlyThe court paused enforcement of SB-261 pending appeal. SB-253 was not enjoined and remains in force.
2026-02-26
CARB adopts initial regulationUnanimous Board vote adopting the initial implementing regulation — fee structure, key definitions, and the first-year reporting deadline.
2026-11-10
First Scope 1 & 2 report due (deadline passed)Inaugural Scope 1 and Scope 2 disclosure for Reporting Entities, covering data for fiscal years ending in 2025. No third-party assurance required for this cycle.
2027
Scope 3 reporting beginsScope 3 disclosure starts, within a statutory window after the Scope 1 and 2 filing; a good-faith safe harbor shields unintentional Scope 3 misstatements through 2030.
2030
Reasonable assuranceAssurance over Scope 1 and 2 ramps to reasonable assurance from 2030 (limited assurance phasing in beforehand, per CARB’s second rulemaking).

Pre-check — are you a Reporting Entity?

SB-253 applies to a “Reporting Entity”: a business entity formed under the laws of California or any other US state (or DC) with more than $1 billion in total annual revenue that does business in California. The revenue test is on total company revenue, not California revenue — which is why the reach is national.

> $1B revenue + does business in CA
Reporting Entity — in scope for SB-253. Report Scope 1 & 2 by 10 Nov 2026, Scope 3 from 2027. reporting.sb_253_261.sb253.threshold.annual_revenue_usd_m
HQ outside California, > $1B, sells in CA
Still in scope. The total-revenue test plus “doing business in California” sweeps in out-of-state and private multinationals. Headquarters location does not exempt you.
$500M – $1B revenue, does business in CA
SB-261 only, not SB-253. Below the $1B emissions-reporting threshold but above the $500M climate-risk threshold — climate-risk disclosure under SB-261 (currently enjoined). reporting.sb_253_261.sb261.threshold.annual_revenue_usd_m
Not collecting data as of 5 Dec 2024
Non-collection statement (last resort). An in-scope entity that was not collecting (or planning to collect) emissions data as of CARB’s 5 Dec 2024 Enforcement Notice may file a statement to that effect for 2026 — but is expected to file a full inventory from 2027.
≤ $500M revenue / no CA business
Out of scope of both laws (voluntary reporting aside). Confirm the “doing business in California” test against CARB’s published definitions for a borderline case.

SB-253 vs SB-261 — two laws, two thresholds, two legal postures

The single most common error is conflating the two California laws. They were enacted together and share the SB-219 amendment, but they impose different obligations on different companies — and right now they have opposite legal standing. This page is about SB-253; SB-261 appears here only for contrast.

SB-253 — live

Emissions disclosure (> $1B revenue)

The Climate Corporate Data Accountability Act. Reporting Entities (> $1B total revenue, doing business in California) disclose Scope 1 and Scope 2 by 10 November 2026 and Scope 3 from 2027, on the GHG Protocol, with assurance ramping to reasonable by 2030. In force; not enjoined.

SB-261 — enjoined

Climate-risk disclosure (> $500M revenue)

The Climate-Related Financial Risk Act. Covered Entities (> $500M revenue) prepare a biennial climate-risk report aligned with TCFD or IFRS S2. Enforcement is paused under the Ninth Circuit’s November 2025 injunction — reporting is currently voluntary, but the law could be reinstated at short notice.

Status: A Live, Imminent Obligation

Most US climate-disclosure coverage in 2026 is about regimes that are stalled — the federal SEC rule was stayed and is proposed for rescission. SB-253 is the exception, and the practical consequence is simple: if you are a Reporting Entity, your first filing was due on 10 November 2026, and the same Scope 1 and 2 inventory on the GHG Protocol is due every year after that.

The reach is wider than the “California” label suggests. The threshold is total company revenue, not California revenue, so a company headquartered anywhere in the US that clears $1 billion and does business in California is in scope. Private companies are included — there is no public-listing requirement. Estimates put the SB-253 population in the thousands of entities.

SB-253’s Scope 1, 2 and 3 are genuine GHG Protocol scopes

Unlike a CBAM embedded-emissions figure or an EU ETS allowance, the emissions SB-253 requires are ordinary GHG Protocol Scope 1 and Scope 2 (Corporate Standard) and Scope 3 (Scope 3 Standard) — the same tonnes a voluntary corporate inventory already computes. SB-253 is a disclosure-and-assurance wrapper, not a new measurement basis. The outside_scopes tag carried on the SB-253 rows in the GreenCalculus data layer marks them as regulatory threshold/framework metadata (the revenue thresholds, the cadence), not as emission factors — it does not mean the law’s emissions sit outside the GHG Protocol scopes.

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When to Use This Methodology

✓ Use this methodology when
  • You are determining whether your company is an SB-253 Reporting Entity (the $1B + doing-business test)
  • You need to build a Scope 1, 2, and 3 inventory for the 10 November 2026 filing and beyond
  • You are planning the assurance ramp (none in 2026 → limited → reasonable by 2030)
  • You are a US issuer reassessing climate disclosure after the federal SEC rule stalled — SB-253 is the live obligation that reaches Scope 3
  • You are mapping SB-253 against IFRS S2 or CSRD to reuse one inventory across regimes
✗ Do not use this methodology when
  • Your revenue is at or below $1B — you are not an SB-253 Reporting Entity (you may still owe SB-261 above $500M)
  • You need the SB-261 climate-risk methodology specifically — that is a distinct, currently-enjoined regime; see the combined SB-253/SB-261 standard
  • You are quantifying a corporate inventory from scratch — use the GHG Protocol directly; SB-253 wraps disclosure around that inventory, it does not replace the accounting method
  • You need legal advice on the “doing business in California” test or penalty exposure — consult counsel; this page is factual reference, not legal advice

Step 1 — Are You a Reporting Entity?

Two conditions must both hold: the revenue threshold and the California-nexus test. Neither is about where you are headquartered.

Total annual revenue > $1 billion? total company revenue, not CA-only
Measured on the entity’s total annual revenue. Public and private companies both count; there is no listing requirement. At or below $1B → not SB-253 (possibly SB-261 above $500M). reporting.sb_253_261.sb253.threshold.annual_revenue_usd_m
Does business in California? per CARB / California definitions
The nexus test, not headquarters. An out-of-state or foreign-parent US entity that does business in California and clears $1B is in scope. Confirm marginal cases against CARB’s published definitions and flow charts.
Both conditions met? revenue AND nexus
Reporting Entity. Scope 1 & 2 first due 10 Nov 2026, then yearly; Scope 3 from 2027. File now if the first report did not go in. Not collecting data as of 5 Dec 2024? A one-time non-collection statement may apply for 2026 — see Step 5.
“Total revenue, not California revenue” is the most underestimated part of the law

SB-253’s threshold is measured on the entity’s total annual revenue worldwide, gated only by the separate “doing business in California” nexus test. A privately held manufacturer headquartered in another state, with modest California sales but over $1 billion in total revenue, is a Reporting Entity. Scoping models that filter on California-sourced revenue, or that assume only public or only California-headquartered companies are covered, will under-count the in-scope population badly.

Step 2 — What to Report, and When

SB-253 phases the scopes: direct and energy-indirect emissions first, value-chain emissions a year later. The dates below are the operative CARB-set and statutory schedule as of mid-2026.

What Scope First report Assurance
Scope 1 & 2 emissions S1 S2 10 November 2026 Live
data for FY ending in 2025		 None required for 2026; limited assurance phasing in from 2027 (per CARB rulemaking)
Scope 3 emissions S3 From 2027 Next
within a statutory window after S1&2		 Good-faith safe harbor on misstatements through 2030
Reasonable assurance (S1 & 2) S1 S2 From 2030 Reasonable assurance — the higher, positive-opinion level

Thresholds and scopes: SB-253 / SB-261 standard. Operative dates and assurance schedule are CARB-regulation-sourced (adopted 26 Feb 2026) and subject to CARB’s second rulemaking — verify later-year dates with CARB.

Scope 3 and the 180-day lag

Scope 3 begins in 2027, reported within a statutory window after the Scope 1 and 2 filing — up to 180 days afterward under the statute, with SB-219 giving CARB discretion over the precise schedule rather than a strict fixed rule. Scope 3 covers value-chain emissions: purchased goods and services, transportation, business travel, use of sold products, and, for financial institutions, financed emissions (Scope 3 Category 15). It is the largest and hardest part of most inventories — which is why the safe harbor matters.

The Scope 3 good-faith safe harbor runs through 2030

Recognising that value-chain data is immature, the statute shields Scope 3 disclosures made on a reasonable basis and in good faith: through 2030, a Reporting Entity is not subject to penalty for a Scope 3 misstatement that was unintentional and reasonably grounded. This does not make Scope 3 optional — it must be reported from 2027 — but it lowers the risk of getting the hardest numbers approximately right while value-chain data quality matures. The safe harbor is specific to Scope 3; it does not extend to late or missing filings.

Step 3 — Calculate on the GHG Protocol

SB-253 does not define its own emissions accounting. It requires disclosure of emissions calculated on the GHG Protocol Corporate Standard for Scope 1 and 2 and the GHG Protocol Scope 3 Standard for Scope 3. The methodology is the standard corporate inventory; SB-253 adds the disclosure wrapper, the deadline, and assurance. The building blocks:

1
Set the organisational boundaryChoose the consolidation approach (typically operational control) and apply it consistently across all scopes.
2
Quantify Scope 1 — direct emissionsStationary and mobile combustion, process emissions, and refrigerant/fugitive releases from owned or controlled sources.
3
Quantify Scope 2 — purchased energyPurchased electricity, steam, heat, and cooling. Report on a location-based basis and, where instruments exist, a market-based basis.
4
Quantify Scope 3 — value chain (from 2027)The fifteen Scope 3 categories, prioritised by materiality — for many companies purchased goods and services and use of sold products dominate.
5
Disclose and (later) assurePublish per CARB’s format; carry the inventory through the assurance ramp (none 2026 → limited → reasonable 2030).

The same inventory satisfies SB-253, IFRS S2, and CSRD ESRS E1 — all rest on the GHG Protocol. Build it once on the Protocol and map it to each regime’s disclosure format, rather than maintaining parallel numbers.

Step 4 — The Assurance Phase-In (None 2026 → Reasonable 2030)

Assurance is the feature most often mis-stated, because the inaugural cycle has none. The ramp: no third-party assurance for the 10 November 2026 Scope 1 and 2 report; limited assurance phasing in from 2027 (per CARB’s second rulemaking); reasonable assurance — the higher, positive-opinion level used for audited financial statements — from 2030. Assurance follows recognised frameworks such as the ISO 14060 family and ISSA 5000. The worked examples below put the scope test and the timeline on a fictional company.

Worked examples

Two determinations for a fictional out-of-state company, NRT Foods Inc. Example 1 runs the Reporting Entity test; Example 2 lays out its reporting-and-assurance timeline. The thresholds are fixed SB-253 statutory values ($1B revenue); the dates are the CARB-set and statutory schedule.

Example 1 The Reporting Entity test — total revenue, not California revenue
Company profile
NRT Foods Inc. — privately held, headquartered in Texas
Total annual revenue: $1.4B  |  California revenue: $90M  |  Operates distribution in CA Threshold test is on total revenue ($1.4B), not the $90M California slice. SB-253 threshold $1B.
Correct test
Total revenue$1.4B
vs $1B thresholdabove
Does business in CAyes
ResultReporting Entity
In scope
S1&2 by 10 Nov 2026; S3 from 2027
The error to avoid
CA revenue only$90M
vs $1B thresholdbelow
Wrong conclusion“out of scope”
Realityin scope
Missed filing
testing on CA revenue under-scopes
NRT Foods is a Reporting Entity: total revenue $1.4B > $1B and it does business in California. Testing on the $90M California slice would wrongly conclude “out of scope” and miss the first deadline of 10 Nov 2026. Headquarters in Texas is irrelevant.
This total-vs-California revenue distinction is the most consequential scoping error under SB-253 and the reason the law reaches far beyond California-based companies.
Example 2 The reporting-and-assurance timeline S1 S2 S3
NRT Foods, now confirmed in scope
Reporting Entity from Example 1
Sequence: scope-by-scope phase-in + assurance ramp Dates are the CARB-set / statutory schedule as of mid-2026; later-year detail is subject to CARB’s second rulemaking.
Scope phase-in
10 Nov 2026S1 & S2 (FY2025 data)
2027+ S3 begins
S3 lag≤ 180 days after S1&2
2026 → 2027
S1&2 first, then S3
Assurance ramp
2026 (first report)none required
from 2027limited (phasing in)
from 2030reasonable
None → 2030
reasonable assurance by 2030
Timeline: S1&2 first due 10 Nov 2026 with no assurance → S3 from 2027 (within ≤180 days of S1&2, CARB-scheduled) under a good-faith safe harbor to 2030 → assurance ramps to reasonable by 2030. The inaugural report carries no third-party assurance obligation.
Do not build a 2026 programme around assurance that is not yet required — but do build the inventory to an assurance-ready standard, because limited and then reasonable assurance arrive quickly afterward.

Step 5 — Penalties, the Safe Harbor & the Non-Collection Statement

SB-253 has teeth, tempered by transition relief. The three things to understand are the penalty ceiling, the Scope 3 safe harbor, and the one-time non-collection option for 2026.

$
Penalty up to $500,000 per entity per reporting yearFor non-filing, late filing, or non-compliant filing. The ceiling is per reporting year, assessed by CARB.
✓
Scope 3 good-faith safe harbor through 2030No penalty for an unintentional Scope 3 misstatement made on a reasonable basis. Lowers the risk of the hardest, least-mature data.
!
Non-collection statement for 2026 (last resort)An in-scope entity not collecting (or planning to collect) data as of CARB’s 5 Dec 2024 Enforcement Notice may file a statement to that effect for 2026 — but is expected to file a full inventory from 2027.
The non-collection statement is narrow, dated, and one-time — not a deferral

It is tied to a specific fact: whether the entity was collecting or planning to collect emissions data as of 5 December 2024. It applies to the 2026 cycle only and does not relieve the obligation to file a full inventory from 2027. Treat it as a genuine last resort for entities caught without data, not as a way to opt out of the first year. And note the safe harbor and the non-collection statement are different mechanisms: the safe harbor addresses Scope 3 misstatement risk from 2027; the non-collection statement addresses a 2026 data gap.

SB-253 vs SB-261, SEC Rule, IFRS S2 & CSRD

Regime Status (Jun 2026) Threshold Emissions scope
SB-253 Live > $1B total revenue + CA nexus Scope 1, 2 & 3
SB-261 Enjoined > $500M revenue + CA nexus Climate-risk report (no emissions)
SEC climate rule Stayed Large accelerated / accelerated filers Scope 1 & 2 only (no Scope 3)
IFRS S2 Live (by jurisdiction) By adopting jurisdiction Scope 1, 2 & 3
CSRD ESRS E1 Live (EU) EU thresholds Scope 1, 2 & 3

The clean mental model: SB-253 is the broadest US obligation actually in force — it reaches Scope 3, where the stayed SEC rule never did. Its sibling SB-261 sits at a lower revenue band ($500M) but covers climate risk rather than emissions, and is currently enjoined. The dual-filing pattern: a company above $1 billion in revenue is exposed to both SB-253 (emissions) and SB-261 (climate risk), an arrangement that mirrors the way CSRD ESRS E1 pairs a full GHG inventory (E1-6) with a transition/risk narrative (E1-9). An SB-253 inventory built on the GHG Protocol is directly reusable for IFRS S2 and CSRD — the same tonnes, mapped to each regime’s format.

What a Calculator Handles vs What You Decide

SB-253 compliance is, underneath the disclosure wrapper, a GHG Protocol inventory. The per-scope calculators below do the conversions; the scoping, boundary, and filing judgements remain yours. California’s companion climate-risk mandate is covered in the SB-261 methodology.

⚙ The inventory calculators handle
✎ You must decide
  • In scope? Total revenue over $1B and doing business in California?
  • Boundary: which consolidation approach, and which entities are inside it?
  • Scope 3 materiality: which of the fifteen categories are significant and reported first?
  • Assurance readiness: is the inventory built to survive limited (then reasonable) assurance?
  • Non-collection: does the 5 Dec 2024 fact pattern apply for 2026?
  • Legal posture: the “doing business” test and penalty exposure — consult counsel

A dedicated SB-253 disclosure calculator is on the GreenCalculus roadmap. Until it ships, assemble the filing from the per-scope inventory calculators above — they already produce the GHG Protocol figures SB-253 requires.

Error Traps — With Consequences

Error What happens Consequence How to avoid
Testing scope on California revenue Applying the $1B threshold to California-sourced revenue instead of total revenue. Wrongly concludes “out of scope”
A $1.4B-total company with $90M CA revenue is in scope; testing the $90M slice misses the 10 Nov 2026 filing and risks a penalty up to $500k.		 Apply the $1B threshold to total annual revenue; use “doing business in California” only as the nexus gate.
Assuming the SB-261 injunction covers SB-253 Treating the Ninth Circuit’s November 2025 injunction as pausing both laws. Missed live obligation
The injunction is SB-261-only; SB-253 is in force; its first deadline was 10 Nov 2026. Standing down on SB-253 is a filing failure.		 The injunction pauses SB-261 enforcement only. Continue SB-253 preparation; verify status with CARB.
Treating SB-253 like the stalled SEC rule Assuming US federal inaction means no US climate-disclosure obligation. Overlooks the live regime
The SEC rule is stayed; SB-253 is not, and it reaches Scope 3. The live US obligation is the state one.		 Map obligations to SB-253 (and CSRD/IFRS S2 where relevant), not to the stayed federal rule.
Building a 2026 assurance programme Commissioning third-party assurance for the inaugural 10 Nov 2026 report. Premature cost
No assurance is required for 2026; it phases in from 2027 toward reasonable by 2030. Effort is better spent on inventory quality.		 Skip assurance for 2026, but build the inventory to an assurance-ready standard for the years that follow.
Treating the non-collection statement as a deferral Using the 2026 non-collection statement to opt out, then doing nothing for 2027. Unprepared for 2027
The statement is tied to the 5 Dec 2024 fact and applies to 2026 only; a full inventory is expected from 2027.		 Use the statement only if the 5 Dec 2024 fact pattern genuinely applies, and start collecting data immediately.
Assuming the Scope 3 safe harbor makes Scope 3 optional Deferring Scope 3 entirely because misstatements are shielded to 2030. Non-compliant from 2027
Scope 3 must be reported from 2027; the safe harbor covers good-faith misstatement, not non-filing.		 Report Scope 3 from 2027; rely on the safe harbor for data-quality risk, not as permission to skip it.
Maintaining a separate “SB-253 inventory” Building SB-253 numbers apart from the corporate GHG Protocol inventory. Duplicated, divergent figures
SB-253 S1/2/3 are genuine GHG Protocol scopes — they should be the same tonnes reused for IFRS S2 and CSRD.		 Build one GHG Protocol inventory; map it to SB-253, IFRS S2, and CSRD formats rather than re-deriving.

Methodology Metadata — For Filing Documentation

Copy into your SB-253 methodology documentation. Threshold values are statutory; the operative dates and assurance schedule are from the CARB initial regulation and are newer than any static dataset — verify the current position with CARB before each cycle.

Methodology GreenCalculus California SB-253 Calculation & Disclosure Methodology v1.1 (June 2026). greencalculus.com/methodology/california-sb-253-methodology/
Governing law Climate Corporate Data Accountability Act (SB-253, 2023), as amended by SB-219 (2024); California Health & Safety Code §38532.
Implementing reg. CARB initial implementing regulation, adopted by unanimous Board vote 26 February 2026 (fee structure, definitions, first-year deadline). A second CARB rulemaking is expected for post-2026 dates, format, and assurance detail.
Who is covered Reporting Entity: a US-formed business entity with more than $1 billion total annual revenue that does business in California. Public and private. Threshold is total revenue, not California revenue.
What & when Scope 1 & 2 by 10 November 2026 (data for FY ending in 2025); Scope 3 from 2027 within a statutory window (≤180 days after Scope 1 & 2, CARB-scheduled).
Measurement basis Emissions on the GHG Protocol Corporate Standard (Scope 1 & 2) and the GHG Protocol Scope 3 Standard (Scope 3). SB-253 adds a disclosure/assurance wrapper, not a new accounting method.
Assurance None for the inaugural 2026 report; limited assurance phasing in from 2027 (per CARB rulemaking); reasonable assurance from 2030. Recognised frameworks include the ISO 14060 family and ISSA 5000.
Enforcement Penalty up to $500,000 per entity per reporting year for non/late/non-compliant filing. Scope 3 good-faith safe harbor through 2030. One-time 2026 non-collection statement tied to the 5 December 2024 Enforcement Notice.
Legal posture SB-253 is in force and not enjoined (the Ninth Circuit’s Nov 2025 injunction applies to SB-261 only). Factual reference, not legal advice — consult counsel on the “doing business” test and penalty exposure, and verify current status with CARB.
California SB-253 (Climate Corporate Data Accountability Act) — GreenCalculus.com
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Does this regime apply to you? Scoping is a separate question from reporting, and the six regimes use six different size tests. For the thresholds side by side — revenue, public float, turnover, balance sheet and headcount — with first reporting years and assurance phase-ins, see Regulatory Thresholds.

Frequently Asked Questions

The first Scope 1 and Scope 2 report was due 10 November 2026, covering data for fiscal years ending in 2025 — a deadline set by CARB’s initial implementing regulation, in force since 12 October 2026. No third-party assurance is required for this inaugural cycle. Assurance phases in afterward: limited assurance from 2027 (per CARB’s second rulemaking) and reasonable assurance from 2030. Scope 3 reporting begins in 2027. Verify later-year dates with CARB, as the second rulemaking will finalise post-2026 detail.

A “Reporting Entity”: a business entity formed under the laws of California or any other US state (or the District of Columbia) with more than $1 billion in total annual revenue that does business in California. Both public and private companies count. Critically, the $1 billion test is measured on total company revenue, not California-sourced revenue, so a company headquartered in another state with relatively modest California sales can be fully in scope. The “doing business in California” nexus is a separate gate; confirm marginal cases against CARB’s published definitions. Companies between $500 million and $1 billion fall under the sibling law SB-261 (climate risk), not SB-253.

No. The Ninth Circuit injunction granted in November 2025 applies only to SB-261, the climate-related financial risk law, pausing its enforcement pending appeal. SB-253, the emissions-disclosure law, was not enjoined and remains in force; its first deadline, 10 November 2026, has passed with no extension announced. This is the most common point of confusion, because the two laws were enacted together and are usually discussed as a pair. Covered companies should continue preparing their SB-253 Scope 1 and 2 inventories. SB-261 reporting is currently voluntary, but the law could be reinstated at short notice depending on the appeal.

Yes — SB-253 requires Scope 1, Scope 2, and Scope 3, with Scope 3 beginning in 2027 (within a statutory window of up to 180 days after the Scope 1 and 2 filing, with CARB setting the precise schedule). To accommodate immature value-chain data, the statute provides a good-faith safe harbor through 2030: a Reporting Entity is not penalised for a Scope 3 misstatement that was unintentional and made on a reasonable basis. The safe harbor reduces the risk of getting hard-to-measure value-chain numbers approximately right, but it does not make Scope 3 optional — it must still be reported from 2027, and the safe harbor does not cover late or missing filings.

Two big differences. First, status: the SEC climate rule was stayed in 2024 and the SEC has proposed to rescind it, so it imposes no current obligation; SB-253 is live; its first reports were due 10 November 2026. Second, scope: the final SEC rule covered only Scope 1 and Scope 2 and only for the largest filers, having dropped Scope 3 entirely, whereas SB-253 reaches Scope 1, 2, and 3 and applies to public and private companies above $1 billion revenue. For most US companies asking “what climate disclosure must we actually do now,” SB-253 — not the federal rule — is the binding answer, and it is the one that reaches the value chain.

SB-253 allows penalties of up to $500,000 per entity per reporting year for non-filing, late filing, or non-compliant filing. Separately, there is a narrow transition mechanism for 2026: an in-scope entity that was not collecting, or planning to collect, emissions data as of CARB’s 5 December 2024 Enforcement Notice may file a non-collection statement on company letterhead for the 2026 cycle instead of a full Scope 1 and 2 report. This is a last resort tied to a specific date, not a deferral — a full inventory is expected from 2027. It is also distinct from the Scope 3 safe harbor, which addresses misstatement risk rather than a data gap.

Yes, and it should. SB-253 requires emissions calculated on the GHG Protocol — the same basis underlying IFRS S2 and CSRD ESRS E1. The disclosure formats differ, but the underlying Scope 1, 2, and 3 tonnes are the same. Build one GHG Protocol inventory to an assurance-ready standard and map it to each regime’s reporting format, rather than maintaining parallel and potentially divergent numbers. A company above $1 billion that does business in California is also exposed to SB-261’s climate-risk report, mirroring the way CSRD pairs a GHG inventory (E1-6) with a transition and risk narrative (E1-9).

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