GHG reporting software for EPA GHG reporting vs California SB 253, and which one you actually need

The short answer: GHG reporting software comes in two kinds, and EPA GHG reporting and California SB 253 each need a different one. EPA's Greenhouse Gas Reporting Program is a facility-level federal filing of direct emissions using methods EPA prescribes, submitted through e-GGRT, due March 10, 2027 for reporting year 2025 after EPA moved it from October 30, 2026. SB 253 is an organization-level GHG Protocol inventory covering Scope 1 and Scope 2, submitted to CARB, due November 10, 2026. Software built for one will not produce the other. If you owe both, you need a Part 98 calculation tool and a corporate carbon accounting platform, and the only thing they genuinely share is the source data underneath.

Until October 13, 2026 those two deadlines sat nine days apart this fall, which is why the question is being asked at all. That day EPA filed an interim final rule moving the federal date to March 10, 2027, so SB 253 now comes first and the federal filing follows four months later. Plenty of US industrial companies owe both. What follows is what each obligation actually tests, where the overlap is real, where it is imaginary, and how to buy without paying twice for the same thing.

The two obligations side by side

Almost every mistake in this area comes from assuming that because both are called emissions reporting, both want the same number. They do not. They do not even use the same unit of account.

Read down the rows and the shape of the problem appears. A facility can have a decade of clean GHGRP filings and still be starting from zero on SB 253, because everything SB 253 cares about above the combustion line, purchased electricity, the entity boundary, the consolidation approach, was never in the federal filing at all.

Do you actually owe both?

Often not, and it is worth checking before you buy anything. The two triggers are unrelated, so the four combinations are all real.

• GHGRP only. A single large industrial site under $1 billion in revenue, or with no California nexus. Common for privately held manufacturers and processors.
• SB 253 only. A billion-dollar services, technology, retail or financial company doing business in California with no facility anywhere near a Part 98 threshold. This is the largest group by headcount.
• Both. Large industrials: cement, refining, chemicals, food processing, utilities. This is the group the rest of this article is written for.
• Neither, yet. Which lasts until a customer or investor asks, and that request has no revenue threshold behind it at all.

The California test catches more out-of-state companies than people expect. Revenue is total company revenue rather than California revenue, and the nexus half is met by California sales above an annually indexed figure, $757,070 for 2025, applied as the lesser of that or 25% of total sales. A billion-dollar Ohio manufacturer with under a million dollars of California sales is inside it. The threshold question is worked through in whether SB 253 applies under $1 billion.

Is EPA GHG reporting still required, or was it cancelled?

Still required. EPA proposed on September 16, 2025 to permanently remove program obligations for 46 source categories and suspend nine Subpart W segments until reporting year 2034. That proposal drew more than 50,000 comments and has never been finalized. EPA said in February 2026 that it anticipated finalizing by July 2026, and July passed with no final rule.

What EPA did finalize was narrower, twice. A rule at 91 FR 9712, effective February 27, 2026, moved the reporting year 2025 deadline from March 31, 2026 to October 30, 2026 and changed nothing else. Then an interim final rule (Federal Register document 2026-20982), placed on public inspection October 13, 2026 and effective on publication October 14, moved it again to March 10, 2027, again changing nothing else, so that EPA has time to act on the reconsideration proposal first. No enforcement discretion or no-action assurance is on the record beyond the new date. The full picture, including the coverage tests and what a submission involves, is on EPA GHG reporting.

SB 253 has its own status caveat and it runs the other way. The November 10, 2026 reporting deadline is firm and CARB is planning enforcement around it, but the July 27, 2026 modification package that carries the fee dates and the recurring-deadline language is still proposed text awaiting review by California's Office of Administrative Law. Neither program is settled. Both are due this fall regardless.

Where the two obligations genuinely overlap

One place, and it is worth being precise about it because vendors oversell the overlap. Your Subpart C stationary combustion data and your SB 253 Scope 1 figure come from the same fuel invoices, the same meters and the same heat content records. Collect that once and you have fed both.

Everything else diverges. The federal filing stops at your own direct emissions; the corporate inventory adds purchased electricity, then the boundary decision, then eventually the value chain. And the two want different global warming potentials for the same physical methane, AR5 at 28 for Part 98 against the AR6 figure of 29.8 that CDP expects, so a number cannot simply be copied across. Getting that conversion wrong quietly is the sort of thing an assurance provider finds in 2027 and nobody can explain.

The boundary question that decides your SB 253 number

GHGRP never asks you where your company ends, because a facility is a physical thing. SB 253 asks exactly that, and the answer is a policy choice with consequences: operational control, financial control or equity share, applied consistently to every entity you hold.

The cases that consume the most time are leased sites, joint ventures and recently acquired entities. Under operational control, whether a leased facility sits inside your inventory usually turns on what the lease actually says about who directs operations and who pays the energy bill, which means somebody has to go and read the terms rather than assume them. Companies with large leased estates often find this is the slowest part of a first inventory, and it is the kind of work where pulling the operative terms out of each lease into a structured summary is what turns a filing-cabinet problem into a data problem. Get the boundary wrong and every figure downstream is restated. The choice is worked through in operational vs financial control.

Which GHG reporting software do you need for each?

Buy for the obligation, not for the word "emissions". "GHG reporting software" is sold under one label for two different jobs: facility filings under EPA's Part 98 rules, and a corporate greenhouse gas inventory under the GHG Protocol for SB 253, CDP or a customer. These are two different product categories that happen to share a vocabulary, and a demo that looks right for one will often be the wrong purchase for the other.

So the best GHG reporting software is two answers. For the EPA filing, it is e-GGRT itself, which is free, plus a Part 98 calculation tool if your sites are complex, often the air emissions module of an EHS suite such as Intelex or Enablon (compared in Intelex vs Enablon). For SB 253, it is a carbon accounting platform that builds a GHG Protocol inventory and keeps the evidence behind every figure. If you are deciding whether an EHS suite should carry both jobs, the trade-offs are on Enablon alternatives.

We should be plain about our own position in that table. CarbonAccounting.ai is not an e-GGRT filing tool and does not compute Subpart C or Subpart W tier calculations. If the federal filing is your only requirement, use e-GGRT or a Part 98 specialist. Where we work is the corporate inventory column: taking the accounts payable, utility and fuel records a business already keeps, classifying them to GHG Protocol scopes, and keeping the link from every total back to the source line. The vendor landscape for that column is compared on best carbon accounting software and specifically against SB 253 requirements in best carbon accounting software for SB 253.

Which one should you build for first?

Build for SB 253, and treat the federal filing as a deadline to hit rather than a capability to invest in. Three reasons, in order of how much money they save.

1. The federal obligation is the one that might disappear. An unfinalized proposal would remove 46 source categories. The California obligation is not under any comparable threat, and SB 253 was not enjoined.
2. The corporate inventory is the one anyone asks you about. No customer, investor or lender has ever asked to see an e-GGRT submission. They ask for a company footprint, and increasingly they ask annually.
3. SB 253 gets harder, not easier. Limited assurance over Scope 1 and Scope 2 begins with 2027 filings, the reporting template becomes mandatory, and Scope 3 arrives. Anything you build to survive assurance now is worth more each year.

The practical sequence for a company that owes both has flipped. Put the boundary and the Scope 2 data first, because they are the part of the November 10 SB 253 report that is genuinely new work. Then file the federal report on the prescribed methods by March 10, 2027, three weeks before the reporting year 2026 report is due on March 31, using the same fuel records. The ninety-day version of that plan is in the SB 253 deadline plan.

If you are working out which obligations actually reach you, climate disclosure software maps the US landscape and California climate disclosure software covers CARB in detail. For the method underneath both, see GHG accounting software, and to watch classification run against a real ledger, try the demo on our carbon accounting software.