SB 253 compliance cost: what CARB estimates the November 10, 2026 report costs per company

The California Air Resources Board estimates that SB 253 compliance costs a covered company $142,711 a year: $87,498 to report Scope 1, 2 and 3 emissions and $55,213 for limited assurance over Scope 1 and Scope 2. Reporting Scope 1 and Scope 2 alone, which is all the first report due November 10, 2026 requires, is estimated at $73,544. A separate annual program fee, estimated in the low thousands per entity, sits on top of those figures.

Those numbers come from CARB's own Standardized Regulatory Impact Assessment, presented at its March 2026 public workshop. They matter because no consultancy in this market publishes a rate card, which leaves finance teams budgeting a legal obligation with no anchor at all. A regulator that had to justify its own rule is the one party with a reason to publish.

What does CARB estimate SB 253 compliance costs?

CARB modelled the ongoing annual cost to a single reporting entity and broke it into reporting and assurance. The reporting line covers building the inventory. The assurance line covers the independent third party who checks it, which under the phase-in begins with reports submitted in 2027.

Read the first two rows carefully, because the difference between them is the real Scope 3 number. Adding all fifteen Scope 3 categories to an existing Scope 1 and 2 inventory costs an estimated $13,954 a year in CARB's model, not another full inventory. That is a smaller increment than most companies assume, and it is consistent with what actually happens in practice: once you have the boundary, the factor policy and a classified ledger, the Scope 3 categories are largely a reuse of work you already did. The expensive parts are the first boundary decision and the assurance.

What does the first year cost?

Year one runs higher because setup happens once. CARB priced three different ways of phasing in Scope 3 from 2027 and produced a first-year figure for each.

CARB has not chosen between these. It put all three out for comment and said formal rulemaking would follow, so treat the spread as a planning range rather than a decision. CARB's own framing of the headline figure is that it represents less than 0.02% of the $1 billion revenue threshold that puts a company in scope, which is true and also not much comfort to the controller who has to find it.

The program fee is separate, and it is due the day before the report

SB 253 and SB 261 are funded by an annual fee charged to the entities they cover. CARB adopted a flat fee, meaning every covered entity pays the same amount rather than a fee scaled to revenue. The amount is set each year by dividing total program cost across the reporting population, so it moves with both. CARB's earlier estimates put it at roughly $3,106 for an SB 253 reporter and $1,403 for an SB 261 reporter, with the adopted structure expected to land somewhere in the low thousands per entity.

The timing is the part worth writing down. CARB issues a written fee determination by September 10 each year, and the fee is due by November 9 to avoid a late charge. That is one day before the November 10 emissions report. Two obligations, two deadlines, one day apart, and they are tracked by different people in most companies. Parent entities may submit a consolidated fee payment on behalf of subsidiaries.

What the November 10, 2026 report actually requires

CARB deferred the first Scope 1 and Scope 2 reporting deadline from August 10, 2026 to November 10, 2026, formally publishing the change on July 27, 2026 through a 15-day comment period that closed on August 11. The extension bought roughly three months, and it did not change what has to be filed.

For 2026 specifically, CARB has said strict compliance with its draft reporting template is not required, and limited assurance is not required. Companies may report Scope 1 and Scope 2 based on information they already possessed or were already collecting as of the December 5, 2024 enforcement notice. The template becomes mandatory with 2027 filings, and limited assurance begins with reports submitted in 2027. CARB plans a voluntary online intake platform for fee contact information and emissions reporting, alongside a guidance document.

There is also a route for companies that genuinely have nothing to file. An entity that was not collecting emissions data and had no plans to collect it when the enforcement notice was issued can submit a statement on company letterhead saying so, explaining its reason and its good-faith efforts. That is not a loophole and it is not costless: it is on the record, it does not apply to 2027, and the statutory penalty framework treats documented good faith as a mitigating factor rather than a defence. What CARB can actually fine you for is set out in SB 253 penalties.

Are you actually covered? The threshold nobody quotes

SB 253 reaches US-organized entities with more than $1 billion in total annual revenue that do business in California. The statute never defines the second half, which is why so much early advice hedged. CARB's regulation fills the gap by borrowing California's existing franchise-tax test: an entity is doing business in the state if it is organized or commercially domiciled there, or if its California sales exceed a set threshold, given as $735,019 for 2024 and indexed each year.

That number is the single most consequential fact in the whole regime for companies outside California. A billion-dollar manufacturer headquartered in Ohio with under a million dollars of California sales is in scope. Consolidation follows the approach used in the Cap-and-Invest program, so subsidiaries roll up to the parent rather than each filing separately. If you have not run this test against your own revenue by state, run it before you budget anything, because the answer decides whether the rest of this page applies to you at all. The threshold arithmetic on the revenue side is covered in do I need to comply with SB 253 under $1 billion.

Which costs you can actually move

Three of CARB's four cost lines have very different elasticity, and knowing which is which is the whole budgeting exercise.

The two large controllable lines are both data problems, not measurement problems. That is why the cheapest defensible first inventory usually starts from accounts payable and utility billing rather than from a data-collection questionnaire: the records already exist, they are already reconciled to the general ledger, and every figure derived from them has a source document attached by construction. The method is in calculating Scope 3 from spend, and what an assurer will ask to see is in limited vs reasonable assurance.

Budget it as a program, not an annual task

The obligation escalates on a published schedule: Scope 1 and 2 with no assurance for 2026, limited assurance over Scope 1 and 2 plus Scope 3 from 2027, and reasonable assurance over Scope 1 and 2 with limited assurance over Scope 3 from 2030. Each step adds cost and, more importantly, adds a documentation standard that is far cheaper to build into the first inventory than to retrofit into the fourth. Companies that handle this well tend to treat the 2026 to 2030 run as a multi-year program with milestones and an owner rather than a report that comes round each autumn, because the decisions that get expensive are the ones deferred.

The practical version of that is unglamorous. Decide the boundary once and write down why. Fix the emission factor set and the global warming potential basis, and record the versions. Keep the link from every reported tonne back to the invoice or meter reading behind it. Do those three things in 2026 and the 2027 assurance engagement is a sampling exercise instead of an excavation, which is where the $55,213 line actually gets cheaper.

Questions finance teams ask

If the number you need to produce is the reason you are reading this, the shortest path is to classify the ledger you already have rather than start a data-collection project. Our carbon accounting software drafts a scope and Scope 3 category for every accounts payable line with a confidence score, routes the uncertain tail to a person, and keeps the invoice attached to the figure so the 2027 assurance engagement has something to sample. The regime in full is on SB 253 reporting software, the tooling budget is on carbon accounting software cost, and the build-versus-buy question is on carbon accounting services.

Cost and fee figures on this page are the California Air Resources Board's own published estimates from its SB 253 Standardized Regulatory Impact Assessment and fee rulemaking materials, as they stood in August 2026, and CARB invited comment on their accuracy. Deadlines, fee amounts and the 2027 Scope 3 approach are subject to further CARB rulemaking, and California climate disclosure remains subject to litigation. Nothing here is legal, accounting or tax advice.