California Emissions Reporting: Thresholds, Deadlines, and Penalties

If your company operates a facility in California or does significant business in the state, you may owe the California Air Resources Board one or more annual emissions reports. California emissions reporting requirements fall into three main buckets: facility-level greenhouse gas reports under the Mandatory Reporting Regulation (MRR), corporate climate disclosures under SB 253 and SB 261 for large companies, and separate criteria pollutant and toxic air contaminant filings under the state’s community air protection work. Deadlines cluster in spring and early summer, and missing them exposes you to daily civil penalties that can reach $10,000 per day.

Who Has to Report Under the MRR

The Regulation for the Mandatory Reporting of Greenhouse Gas Emissions sits at Title 17 of the California Code of Regulations, sections 95100 through 95163, and CARB administers it.¹ It reaches three groups: facility operators, fuel suppliers, and electric power entities.

Some industries must report no matter how little they emit. Petroleum refineries, cement plants, lime manufacturers, nitric acid producers, and electricity generators subject to federal continuous emissions monitoring all report automatically. For other industries, the trigger is 10,000 metric tons of CO2 equivalent per year from stationary combustion and process emissions combined. That category includes glass production, hydrogen production, iron and steel manufacturing, pulp and paper facilities, petroleum and natural gas systems, and geothermal electricity generation.²

Fuel suppliers hit the same 10,000 metric ton threshold, but the math is different. If the annual fuel you produce, import, or deliver into California would release 10,000 or more metric tons of CO2e when fully combusted, you report. This captures terminal operators delivering petroleum fuels, natural gas pipeline operators, and importers of liquefied petroleum gas, compressed natural gas, and liquefied natural gas.²

Abbreviated Reporting Between 10,000 and 25,000 Metric Tons

Facilities emitting between 10,000 and 25,000 metric tons of CO2e can file an abbreviated report using simpler calculation methods. Abbreviated reporters are not subject to third-party verification, missing data substitution rules, or the stricter calibration and accuracy requirements that apply to larger emitters.³ They still must include both fuel combustion and process emissions in the report and in the threshold comparison.

Corporate Climate Disclosures for Large Companies

The MRR focuses on physical facilities. Two newer laws reach corporations based on revenue instead.

The Climate Corporate Data Accountability Act (SB 253), codified at Health and Safety Code section 38532, applies to any business entity doing business in California with total annual revenues exceeding $1 billion, measured by the entity’s prior fiscal year. It reaches partnerships, corporations, LLCs, and other business entities regardless of where they are incorporated.⁴

Covered companies must publicly disclose three categories of greenhouse gas emissions:

Scope 1, meaning direct emissions from sources the company owns or controls, such as fuel burned in company-owned boilers or vehicles.
Scope 2, meaning indirect emissions from purchased electricity, steam, heating, or cooling.
Scope 3, meaning all other indirect emissions across the value chain, including purchased goods and services, business travel, employee commuting, and the use of sold products.

Scope 1 and Scope 2 reporting began in 2026. Scope 3 reporting is required starting in 2027. Emissions must be calculated in conformance with the Greenhouse Gas Protocol. Independent assurance is also required: limited assurance for Scope 1 and Scope 2 starting in 2026, escalating to reasonable assurance in 2030, with Scope 3 assurance beginning at a limited level in 2030.⁴

The companion Climate-Related Financial Risk Act (SB 261), at Health and Safety Code section 38533, applies at a lower revenue threshold: $500 million in annual revenue. Instead of emissions figures, SB 261 requires a biennial report on climate-related financial risks and the measures adopted to reduce or adapt to them, following the Task Force on Climate-related Financial Disclosures framework, the IFRS S2 standard, or an equivalent framework from a governmental entity. Insurance companies regulated by the California Department of Insurance or operating in the business of insurance in any other state are exempt.⁵

One important status update: the U.S. Court of Appeals for the Ninth Circuit granted an injunction in November 2025 pausing enforcement of SB 261. A similar motion against SB 253 was denied. As of early 2026, CARB confirmed it will not enforce SB 261 while the injunction remains in effect, but SB 253 obligations continue on schedule.

Criteria Pollutants and Toxic Air Contaminants

Greenhouse gases aren’t the only emissions California tracks. The Criteria Pollutant and Toxic Air Contaminant Reporting regulation, developed to implement Assembly Bill 617, establishes statewide annual reporting for pollutants like nitrogen oxides, particulate matter, and toxic air contaminants from stationary sources.⁶ Facilities in or near designated AB 617 communities face heightened monitoring obligations, including potential fence-line monitoring. Smaller commercial operations are generally exempt unless they use specific chemical processes or large-scale combustion equipment, but the local air district where a facility operates can impose additional requirements beyond the state baseline.

Deadlines You Need to Hit

California keeps a strict annual calendar for MRR filings. For 2025 data reported in 2026, the deadlines are:

April 10: reports due from facilities and fuel suppliers, including electricity generators, refineries, cement plants, and facilities emitting over 25,000 metric tons of CO2e from combustion sources.⁷
June 1: reports due from electric power entities and facilities subject to abbreviated reporting.⁷
August 10: final third-party verification statements due for all reports, covering emissions data, supplier data, and product data.⁷

Electric power entities also face a specified source registration deadline, typically February 1 (February 2 in 2026 because of the weekend).⁸

For SB 253, the statute directs CARB to set the specific filing date. Scope 1 and Scope 2 reports are due beginning in 2026, with annual Scope 3 reports starting in 2027.⁴ CTR reporting for criteria pollutants and toxic air contaminants generally follows a similar spring timeline, though local air district requirements can shift specific dates.

How to File and Who Verifies

All MRR greenhouse gas reports go through the California Electronic Greenhouse Gas Reporting Tool, Cal e-GGRT. The portal also handles reporting under the oil and gas regulation and the gas-insulated equipment regulation.⁹ A facility representative registers for an account, assigns roles for data entry and certification, uploads finalized calculations and supporting documentation, and finishes with a legally binding electronic signature from a designated official. The system runs automated checks for errors, missing fields, and inconsistencies before accepting the submission, and it generates a confirmation receipt you should retain.¹⁰

Facilities emitting 25,000 metric tons of CO2e or more must have their reports reviewed by an accredited third-party verifier before CARB considers the filing complete. The verifier checks whether emission factors were applied correctly, whether monitoring equipment was properly calibrated, and whether the reported figures are free from material misstatement. Facilities in the abbreviated tier (10,000 to 25,000 metric tons) are exempt from third-party verification,³ though CARB can still review any report and request additional documentation. If a verification audit produces a negative finding, the verifier must submit a corrective action plan to CARB including a root cause analysis and timeline for resolving the issues.¹¹

Penalties for Missing or Botching a Report

Health and Safety Code section 38580 ties MRR reporting violations into the main air enforcement regime in sections 42400 through 42402. Any violation of a CARB reporting rule is treated as an emission of an air contaminant for penalty purposes.¹²

On the criminal side, a basic violation is a misdemeanor punishable by a fine of up to $5,000 per day or up to six months in county jail. If the violation causes actual injury to the health or safety of a considerable number of people, the fine rises to $15,000 per day and the maximum jail term extends to nine months.¹³

On the civil side, section 42402 authorizes strict liability penalties of up to $5,000 per day for a basic violation and up to $10,000 per day for standard violations, with penalties of up to $15,000 per day for violations causing actual health or safety injury.¹⁴ Each day counts as a separate offense, so penalties compound fast.¹³ A facility that misses the April 10 deadline and doesn’t cure the violation for 30 days could face civil exposure of $150,000 to $300,000 before anyone looks at whether the data itself is accurate.

SB 253 uses a different structure. Administrative penalties are capped at $500,000 per reporting entity per year, and between 2027 and 2030 Scope 3 penalties apply only for outright failure to file, not for inaccuracies in the data.⁴ SB 261 penalties are capped at $50,000 per year, with enforcement currently paused by the Ninth Circuit injunction.⁵

Record Retention and the Cap-and-Trade Connection

Keep every piece of your reporting file. Facilities must retain all emissions data, calculation records, and submitted reports for at least 10 consecutive years and must produce them within 20 calendar days of a written request from CARB. The retention requirement covers copies of all data and reports filed under the MRR, records used to calculate compliance obligations, and all verification statements and detailed verification reports.

The 10-year window matters more than it might look, because MRR data feeds directly into California’s cap-and-trade program. To be eligible for free allowance allocations, an industrial facility must have complied with all MRR requirements.¹⁵ CARB uses verified production data from MRR filings to determine each facility’s initial allocation and then adjusts the final allocation through a true-up once that year’s data has been verified. Inaccurate or late MRR filings don’t just trigger fines. They can cost a facility its free allowances, which carry real economic value under cap-and-trade.

1
Legal Information Institute. California Code of Regulations Title 17 Section 95100 – Purpose and Scope
2
Legal Information Institute. California Code of Regulations Title 17 Section 95101 – Applicability
3
California Air Resources Board. Reporting Guidance for Determining Rule Applicability
4
California Legislative Information. California Health and Safety Code HSC 38532
5
California Legislative Information. California Health and Safety Code HSC 38533
6
California Air Resources Board. Community Air Protection Program
7
California Air Resources Board. Mandatory GHG Reporting – Key Dates and Activities
8
California Air Resources Board. Mandatory Greenhouse Gas Emissions Reporting – Electric Power Entities
9
California Air Resources Board. Cal e-GGRT
10
California Air Resources Board. Mandatory Greenhouse Gas Reporting – Online Reporting Tool
11
California Air Resources Board. CARB Findings of Verification Services Audit
12
California Legislative Information. California Health and Safety Code HSC 38580
13
California Legislative Information. California Health and Safety Code HSC 42400
14
California Legislative Information. California Health and Safety Code HSC 42402
15
California Air Resources Board. Allowance Allocation to Industrial Facilities