Your customer is about to ask you for a carbon number. Here is what is actually happening.

What the law actually says

California Senate Bill 253, the Climate Corporate Data Accountability Act, applies to US companies with more than one billion dollars in annual revenue that do business in California.¹ Not to you. The threshold is high on purpose.

Those companies have to report their Scope 1 and Scope 2 emissions.³ Scope 1 is what they burn directly, like natural gas in a furnace or fuel in their own trucks. Scope 2 is the electricity they buy. The first report was originally set for August 10, 2026. In June, CARB withdrew its implementing regulation to make clarifying changes and proposed moving that date to November 10, 2026.² As of early August that revision is still in a public comment period, so treat the date as proposed rather than settled.

Then comes 2027, and Scope 3.

Scope 3 is everything else in a company's value chain. For a manufacturer that includes the things they buy from their suppliers. From you.

Why this lands on your desk

Here is the part worth understanding clearly, because it is easy to get wrong in both directions.

SB 253 does not legally require you to report anything. If you are a thirty person shop in Hayward, the law imposes no obligation on you whatsoever. Anyone who tells you otherwise is either confused or selling something.

What the law does is require your large customer to measure emissions across their value chain. And the most practical way for them to do that is to ask their suppliers directly.

So the request does not arrive as a legal demand. It arrives as an email from a procurement contact asking you to fill out a form. Or as a new section in a bid package. Or as a line item on a vendor qualification questionnaire that used to only ask about ISO certification and insurance.

This is already how it works with CDP supply chain requests and EcoVadis ratings. SB 253 adds a large new group of companies that suddenly need supplier numbers they did not need before.

What actually happens when the request arrives

The email lands with a two week deadline. It goes to whoever answers the general inbox, gets forwarded twice, and ends up with an operations manager who has never heard the phrase Scope 2. There is a spreadsheet attached with terms like emission factor, activity data, and reporting boundary.

The company then does one of three things.

They ignore it, and hope it goes away. Sometimes it does. Sometimes the account gets flagged.

They guess. Somebody puts a plausible looking number in the box. This is the worst outcome, because a wrong number is harder to fix than no number, and if the customer's own report gets checked later, your figure gets checked too.

Or they scramble. Someone spends two weeks digging through a filing cabinet for twelve months of utility bills, which turn out to be missing three months, and two of the meters belong to a unit they moved out of in March.

The unglamorous truth about getting ready

The good news is that Scope 1 and Scope 2 for a single site business is not complicated. It is arithmetic. You take how much electricity you used, multiply it by a published factor for your region, and you have Scope 2. You take how much natural gas you burned, multiply it by a published factor, and you have most of Scope 1.

The hard part is not the math. It is the paperwork.

Twelve consecutive months of bills for every meter. Billing periods that do not line up with calendar months. Estimated reads that later get corrected. A meter that changed account numbers. A site you added in June. Knowing whether that propane tank and those two delivery vans count, because they do.

This is why the scramble version takes two weeks and produces a number nobody trusts. Not because carbon accounting is hard, but because nobody keeps utility records in a form that answers the question.

What I would do if I were you

Not much, honestly. Not yet. But three things are cheap.

Find out if your electric and gas utility offers twelve months of usage history through your online account. Most do. Download it. That single step removes the worst part of the scramble.

Write down what you burn on site besides electricity. Natural gas, propane, diesel for a generator, fuel for company vehicles. Just the list, not the numbers.

And if you get one of these requests, do not guess. A number you cannot explain is worse than asking for two more weeks.

The point

"Nobody asks us for that" is a true statement about right now and a poor prediction about 2027. The difference between those two matters a lot to a small supplier.

The companies that handle this well will not be the ones with the best carbon strategy. They will be the ones who had their bills in a folder.