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Regulatory Framework · California · For Suppliers

Your customer is covered by SB 253. Here's what they need from you.

SB 253 binds your customer, not you. But their obligation is exactly why a request landed in your inbox. Here is what it actually asks for, a four-step way to answer it, and what you can reasonably decline.

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Prepare your Scope 1 & 2 figuresWhat SB 253 actually says

Orientation only, current at the review date above. This page is not legal advice and does not replace your customer's own instructions.

The short version
  • You are not in scope. SB 253 binds your customer, not you — there is no such thing as an SME being “SB 253 compliant”.
  • What they're actually asking for: your Scope 1 and Scope 2 emissions, as an input to their own Scope 3 figure.
  • A four-step response: confirm the ask, gather activity data, calculate with a sourced factor, reply with a reusable link.
  • You can reasonably decline third-party assurance, a bespoke template for every customer, and — usually — your own Scope 3.
  • Full explainer: California SB 253 & SB 261. Current timeline: the November 2026 deadline reset.

Why your customer is asking you this

Your customer almost certainly falls, or expects to fall, within SB 253's scope — a large company doing business in California above roughly $1 billion in revenue (see who is actually covered for the exact test). Once a company is in scope, it eventually has to report Scope 3: the emissions across its value chain, including everything it buys. The only practical way to get that number is to ask the businesses it buys from — which is why an SME with no connection to California can still receive an “SB 253 request”.

That is the entire mechanism. Nothing about it makes your business a filer, and nothing about it creates a legal obligation on your side — see the full SB 253 & SB 261 explainer if you want the underlying law itself rather than what to do about it.

What to actually send back

Strip away the covering letter, and almost every SB-253-driven supplier request wants one thing: your Scope 1 (direct) and Scope 2 (purchased electricity) emissions for a stated period, in metric tons of CO2e, with the activity data and emission factor behind the number named. That feeds directly into your customer's own Scope 3 accounting — see our Scope 3 guide if you want to understand where your number lands in their total.

The four-step response

Confirm what's actually being asked

Customers often say "SB 253" loosely for any climate-data request. Read the actual questions — most first-round requests want Scope 1 and Scope 2 only, not a filing on your part.

Gather your activity data

Fuel receipts, vehicle mileage, and utility bills — the inputs behind Scope 1 (direct) and Scope 2 (purchased electricity) emissions.

Calculate with a sourced factor

Apply a published, named emission factor rather than an estimate — see the Methodology page for how United States factors are applied.

Respond with a reusable link

A Passport answers this request and the next one, instead of a new spreadsheet for every customer that asks.

What you can push back on

Answering well does not mean answering everything asked. A standard request does not entitle a customer to third-party assurance on your figures, a bespoke spreadsheet format for every single customer, or your own suppliers' emissions data. See our note on the proportionate scope of buyer requests for where a reasonable line generally sits, and our guide on answering a supplier ESG questionnaire if the request goes beyond emissions data alone.

Common questions

No. SB 253 creates obligations for the company that files with CARB — your customer, not you. There is no such thing as an SME being "SB 253 compliant", because the law does not address SME suppliers at all. What reaches you is a private request: your customer needs your Scope 1 and Scope 2 figures to complete its own value-chain (Scope 3) picture, and asking suppliers directly is the only practical way to get that number.

In almost every case: your Scope 1 (direct) and Scope 2 (purchased electricity) emissions for a stated period, in metric tons of CO2e, with the activity data and emission factor behind the number named. That is what feeds a customer's own Scope 3 figure — see our Scope 3 guide for how the categories work. If a request also asks about your own suppliers' emissions, that is a separate and much larger ask; answer what you can and say plainly where your data ends.

Not for a standard supplier request. Assurance is something your customer's own auditor applies to the customer's consolidated disclosure, not something typically required at the supplier level. A clearly sourced, self-reported figure — with the calculation method and factor stated — is what most Scope 3 data-collection requests are actually asking for. If a specific customer's request explicitly requires assurance, confirm that as a contractual term directly with them rather than assuming it from SB 253 itself.

That is a separate and much larger request than Scope 1 and Scope 2 — your Scope 3 would mean the emissions of your own suppliers, a different data-collection exercise entirely. Most first-round supplier requests stop at Scope 1 and Scope 2 for exactly this reason. If a request goes further, see our guide on answering a supplier ESG questionnaire and on the proportionate scope of buyer requests.

The filing deadline belongs to your customer, not you. See our SB 253 deadline update for the current CARB timeline, which has moved more than once. Your own deadline is whatever your customer's request states — usually earlier than CARB's date, so their team has time to assemble the full value-chain figure before they file.

EcoDiligence turns your energy and fuel data into Scope 1 and Scope 2 emissions using sourced United States grid factors, and produces an SB 253-aligned Passport — a shareable link, a branded PDF, and machine-readable exports — that you can send once and reuse for every customer that asks. It is self-reported and clearly marked as not independently assured.

Reviewed on September 7, 2026. This page explains how to respond to a customer request driven by SB 253 — it is not legal advice and does not state your customer's specific requirements, which take precedence over anything summarised here. For the underlying law, see California SB 253 & SB 261.

EcoDiligence ESG Passports are self-reported summaries structured for ESG disclosure workflows. Content is not independently assured. Information aligned with EFRAG VSME and IFRS S2 (ISSB) frameworks does not constitute formal compliance or certification.

Answer it once, then send a link

Scope 1 and Scope 2, sourced and structured at a permanent URL — so the next customer request is a reply, not a project. Free to start.

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