B Lab Climate Action Standards: Scope 3 Requirements for Larger B Corps (2026 Guide)

At a glance

B Lab's new Climate Action Impact Topic requires larger B Corps to:

• Measure Scope 1, 2, and 3 GHG emissions
• Have their GHG inventory verified by an accredited third party
• Set science-based targets validated by SBTi or an independent third party
• Develop a climate action plan aligned with limiting global warming to 1.5°C

For B Corps recertifying in the next 12-18 months, the data collection work should be underway now. Inventories built on spend-based accounting or industry-average emissions factors won't meet the new verification bar.

What are B Lab's new Climate Action standards?

B Lab's new Climate Action Impact Topic, part of the standards released in 2025, raises the measurement bar for Certified B Corporations. Larger companies are now required to measure Scope 1, 2, and 3 emissions, verify their GHG inventory through an accredited third party, and validate their science-based targets through SBTi or an independent verifier.

The new standards replace a framework where Scope 3 measurement was encouraged but not mandatory. Under the updated rules, Scope 3 is in scope at the larger-company level, and verification is required before SBTi will validate any target.

Three of the four new requirements touch measurement. That's where the work is, and where most B Corps underestimate the lift.

Which B Corps need to measure Scope 3?

B Lab's new standards apply different requirements to different company sizes. Larger companies carry the heavier measurement lift, including mandatory Scope 1, 2, and 3 and third-party verification. Smaller and mid-sized B Corps have lighter requirements focused on climate action plans and measurable targets that don't explicitly depend on GHG measurement.

Check your specific obligations directly against B Lab's published standards documentation. If you're a consumer brand above 250 employees or $75M+ in annual revenue, assume the full set of requirements applies to you until confirmed otherwise.

Why Scope 3 is the hardest part

For consumer brands, Scope 3 typically represents 70 to 90 percent of the total footprint. Purchased goods and services, upstream transportation, and end-of-life handling usually dominate the inventory. Most of the B Corps we talk to already know this.

What surprises them is that the inventories they built two or three years ago, using spend-based accounting or industry-average emissions factors, no longer meet the bar.

There are two reasons.

The first is validation. SBTi will validate targets, but only against an inventory that reflects a company's actual supply chain. An inventory built on generic proxies shows the industry average for a category of products. That average can be off by a factor of two or more compared to a specific supplier's actual footprint. When the target you set is based on the wrong baseline, the reductions you commit to won't match what your supply chain can actually deliver.

The second is verification. B Lab now requires the inventory itself to be verified by an accredited third party before SBTi validation. Verifiers will ask where your emissions factors came from. Proxy-based inventories are harder to defend in that conversation, especially for material categories.

What does "audit-ready" Scope 3 look like?

1. A documented audit trail. Every emissions calculation is traceable back to its source, with assumptions written down and version-controlled. If a verifier asks where a number came from, you should be able to point to the document.
2. GHG Protocol-aligned methodology. Clearly defined system boundaries for which upstream and downstream categories are included, with calculation methods that follow GHG Protocol Corporate Standard and Scope 3 Standard. Ambiguity is what gets flagged.
3. Primary supplier data for material categories. For the 10 to 20 percent of your spend driving the majority of your footprint, you need supplier-specific data — product-level LCAs or Product Carbon Footprints. Generic emissions factors are acceptable for the long tail. They aren't acceptable for your biggest drivers.
4. Documented data gaps. Where you're using EcoInvent or other secondary emission factors, the reliance needs to be explained in the inventory documentation. Verifiers don't expect perfect primary data on day one. They do expect you to know where the gaps are and why.

For LCA-based inputs feeding into your inventory, ISO 14040/44 critical review is required before those LCAs can be published. Most verifiers will ask about it during inventory verification.

Learn more about how Planet FWD builds Corporate Inventories and Scope 3 decarbonization programs.

How to plan backward from your recertification date

Working backwards from a typical recertification timeline:

•8 to 12 weeks for a corporate greenhouse gas inventory, depending on scope
• 4 to 8 weeks for inventory verification
• SBTi target validation can take several months depending on their current queue
• A full year of underlying data before any of that starts

If you're recertifying in 2026, the data collection work should be underway now. If you're recertifying in 2027, you have a narrow window to get the methodology right before it affects your validation timeline.

Three questions to ask if you're starting today

1. What are your biggest Scope 3 categories? A spend-based screening gets you there in a week. Focus the primary data effort where it matters.
   
   
2. What data do your suppliers already have? Large food and personal care suppliers increasingly have Product Carbon Footprint data available. If you're working with a platform that can ingest that data directly, timelines compress significantly.
   
   
3. Who is going to review the methodology? ISO 14040/44 requires critical review for any LCA work feeding into your inventory. Build it in from day one. It's faster and cheaper than retrofitting.
   

How fellow B Corps are approaching this

Ritual, a Certified B Corporation working toward net zero by 2030, had previously done spend-based corporate carbon accounting. They partnered with Planet FWD to build product-level LCAs across their full portfolio, then used that data as the foundation for an annual Corporate Inventory. Their Chief Impact Officer, Lindsay Dahl, on the approach:

"Having previously done spend-based corporate carbon accounting, we wanted a more accurate understanding of our Scope 1, 2 and 3 emissions. Marrying the product LCAs with corporate carbon accounting with Planet FWD will be best in class."

Read the full Ritual case study →

Thrive Market took a similar path. They'd built an emissions baseline with a previous partner, but their tools weren't fully capturing the real climate benefit of their regenerative and better-than-ingredient sourcing. With Planet FWD, they expanded their GHG inventory with supplier-specific data and uncovered insights their previous tools had missed — like their Australian grass-fed beef being lower-emissions than conventional alternatives despite the transportation distance.

Read the full Thrive Market case study →

How Planet FWD fits

We build ISO 14040/44 compliant LCAs and full Corporate Inventories (Scope 1, 2, 3) for consumer brands. Product-level LCAs and Corporate Inventory work live on one platform, which means the data you collect once is reusable across B Corp recertification, SBTi validation, and retail sustainability requests. Third-party critical review is built into our process, not a separate vendor engagement.

Other B Corp customers include Just Salad, Amika, Horizon Organic Dairy, and Patagonia.

If you're preparing for B Corp recertification in the next 12 to 18 months and want to talk through where your inventory stands today, Steven LeCamu on our team runs 30-minute scoping calls.

Book a call →

Frequently asked questions

What is B Lab's Climate Action Impact Topic?

The Climate Action Impact Topic is one of seven Impact Topics in B Lab's new standards, released in 2025. It defines the climate-related performance requirements a company must meet to achieve and maintain B Corp Certification. For larger companies, this includes a climate action plan aligned with limiting global warming to 1.5°C, measurement of Scope 1, 2, and 3 emissions, inventory verification by an accredited third party, and science-based targets validated by SBTi or verified by an independent third party.

Which B Corps are required to measure Scope 3?

Larger B Corps face the full set of Scope 1, 2, and 3 measurement requirements under the new standards. Smaller and mid-sized B Corps have lighter requirements focused on climate action plans and measurable targets that don't depend on complete GHG measurement. For specific size thresholds, reference B Lab's published standards documentation. Consumer brands above 250 employees or $75M+ in annual revenue should assume the full requirements apply.

How long does B Corp Scope 3 verification take?

Typical timeline from start to verification:

• 8 to 12 weeks for a corporate greenhouse gas inventory, depending on scope
• 4 to 8 weeks for inventory verification
• Several additional months for SBTi target validation, depending on their current queue

A full year of underlying supply chain data is needed before any of this starts.

Will spend-based Scope 3 data meet B Lab's new requirements?

For larger B Corps, spend-based accounting likely won't meet the verification bar for material categories. SBTi validates targets against inventories that reflect actual supply chain data, and third-party verifiers will ask for primary data or supplier-specific Product Carbon Footprints for the 10-20% of spend driving the majority of emissions. Spend-based factors remain acceptable for the long tail.

When do the new B Lab Climate Action standards take effect?

The new standards were released in 2025 and are already being applied to recertifications on a rolling basis. Reference B Lab's published standards documentation for the specific rollout timeline affecting your recertification window.

What is SBTi validation and why does it matter for B Corps?

The Science Based Targets initiative (SBTi) is the global standard-setter for corporate climate targets. Under B Lab's new standards, larger B Corps must have their science-based targets validated by SBTi or verified by an independent third party. SBTi validation requires a verified GHG inventory as the foundation for target-setting.

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