If you run a plant in Michigan, Ohio or Indiana, California climate rules probably sit pretty low on your list. Fair enough. But November 10, 2026 marks the first filing deadline for California's SB 253, and the ripple effects reach a lot further than the state line.
Here's the short version: most mid-sized manufacturers won't have to file anything with California this year. Plenty of them will still feel it, because their biggest customers do have to file. And those customers are already asking their suppliers for emissions data.
What SB 253 actually requires
SB 253, the Climate Corporate Data Accountability Act, was signed in 2023. It requires companies that do business in California and bring in more than $1 billion in total annual revenue to publicly report their greenhouse gas emissions every year.
Two details matter here:
The $1 billion is total revenue, not California revenue. A Grand Rapids company with $1.2B in sales and a small slice of business in California counts.
"Doing business in California" is a low bar. It's based on the state's tax code: sales, property or payroll in California above set thresholds. A sales office, a distribution point or a handful of employees there can be enough.
The first report covers Scope 1 emissions (fuel you burn on site and in your fleet, plus refrigerant leaks) and Scope 2 emissions (the electricity, steam and heat you buy). For most companies on a calendar year, that means 2025 data.
The deadline moved once already. California's Air Resources Board (CARB) pushed it from August 10 to November 10 back in June, and it published filing guidance and a voluntary intake platform in September. California finalized the regulations on October 12, locking in the November 10 date. Then on November 9, a federal appeals court let the Scope 1 and 2 reporting move ahead but said the Scope 3 piece is likely unconstitutional. Expect Scope 3 to be put on hold while the courts sort it out.
"We're nowhere near $1 billion. Why should I care?"
Because of Scope 3.
Scope 3 covers emissions in a company's value chain, which includes everything it buys from suppliers. SB 253 was set to add Scope 3 starting in 2027, and that's now likely on hold after the November 9 ruling.
That doesn't make the questions go away. Many large companies already report Scope 3 through CDP or have supply chain targets of their own, and purchased goods and services is usually their biggest category.
If you make components, packaging, materials or finished goods for a large company, your emissions are part of their purchased goods number. They can estimate it with industry averages, or they can ask you for real data. More and more of them are asking.
So even if SB 253 never applies to you directly, here's what tends to show up:
A supplier questionnaire asking for your Scope 1 and 2 totals
A request to report through a platform like CDP or a customer portal
A question about whether you have reduction targets
Eventually, a preference for suppliers who can answer all of the above
None of this is a legal requirement for you. It's a business requirement coming from the people who buy from you, which is often harder to ignore.
What a good answer looks like
When a customer asks for your emissions, they want three things: a number, a method and a sense that the number will hold up next year. In 2027, large reporters move into third-party "limited assurance" on their data. That means their auditors start looking harder at where the inputs came from, including yours.
The good news is that Scope 1 and 2 for a manufacturer are pretty manageable. Most of the data already exists in your utility bills, fuel invoices and maintenance records. The work is pulling it together the same way every year and documenting how you got there. (We broke down what goes into Scope 1 and 2 data collection a while back. It still holds up.)
Five things to do before your customers ask
Check whether you're in scope yourself. If your company or parent company tops $1B in revenue and has any California footprint, talk to your finance and legal teams now. The first deadline is November 10, 2026. If you still need to submit your Scope 1 and 2 emissions to CARB, you can do it online through CARB's reporting intake platform, or by email at climatedisclosure@arb.ca.gov.
Find out what your top customers have committed to. Look at their sustainability reports or CDP responses. If they've set supply chain targets, data requests are coming.
Gather 12 months of energy and fuel data. Electricity, natural gas, propane, diesel and fleet fuel for every site. Use usage numbers, not just dollar amounts.
Don't forget refrigerants. Leaks from HVAC and process cooling count as Scope 1 and are easy to miss.
Write down your method. Which sites, which year, which emission factors. A one-page record now saves a scramble when the second request comes in.
The bottom line
SB 253 is California's law, but supply chains don't stop at the state line. The manufacturers who have a clean, repeatable emissions number ready will answer customer requests in an afternoon. Everyone else will be doing it from scratch under a deadline.
Not sure where your GHG data stands? Let's talk through it.