B Lab Climate Action (v2.1): what Small & Medium vs Large companies need to know

Climate expectations for B Corps have stepped up following the launch of the new standards in 2025. If you’re preparing to certify or recertify, you'll need to know when requirements apply and which ones apply to your comapny size. This guide focuses on organisations Large and below and keeps the emphasis on practical next steps.

30-second refresher – what's changed?

Minimums, not points – Certification now rests on meeting minimum requirements across seven Impact Topics. That's right - no more scoring! Just a minimum requirement threshold.
Phased over time – Climate Action requirements “switch on” at Year 0, then Year 3, then Year 5.
Size-scaled – Small & Medium follow one path; Large has a higher bar from Year 0.
Verification for Large – Annual independent third-party verification of the GHG inventory.
SME requirements a bit unclear... – Small & Medium are not required to measure emissions, yet must publish 'progress' by Year 3 – something that's hard to do credibly without data.

Version timeline

If you're struggling to keep up to date with changes, you're not alone. Here's a summary of recent updates, and when you should head for the latest version).

8 Apr 2025 – B Lab launched the new B Corp Standards, replacing the points model with minimum requirements across seven Impact Topics.
12 Aug 2025 – v2.1 published with clarifications and fixes.
Official text – The official PDF on B Lab’s download page is the go-to version.

How to read Climate Action

The new standards use two dimensions to keep everything tidy:

Time – When requirements apply: Year 0, Year 3, Year 5.
Code – What the requirement is:
- CA1.x = Measure & disclose (your GHG inventory + public reporting)
- CA2.x = Plan & targets (Climate Action Plan or Transition Plan, plus science-based targets)
- CA3.x = Implement & report (deliver your plan, just transition, ongoing disclosures)

Size matters – B Lab assigns size by workers or revenue, whichever is higher. Small & Medium share the same Climate Action path; Large has extra requirements from Year 0.

Size boundaries (quick reference)

B Lab assigns size by workers or revenue – whichever is higher. Thresholds are in USD; workers are FTE. You can read more about these definitions directly from B Corp here.

Assign the higher category if workers and revenue point to different tiers.

Small & Medium requirements

Plain-English summary – Publish a Climate Action Plan at Year 0. By Year 3, demonstrate and publish progress versus plan. Measuring a full Scope 1–3 footprint isn’t mandated, but it’s the most credible way to evidence Year-3 progress and satisfy customer requests.

Small & Medium requirements at a glance

Small & Medium B Corp Climate Action Requirements

A note on credibility

1.5 °C is the threshold the IPCC has identified as the upper limit we should be aiming toward globally if we’re to avoid the worst impacts of climate change. The Science Based Targets initiative (SBTi) translated that limit into required action on behalf of businesses: an absolute reduction in full-scope emissions of at least 90% by 2050, offsetting the remainder.

These are highly specific targets and frameworks, backed by climate science. By contrast, B Corp asks small and medium businesses to commit to:

'supporting the global ambition to limit global warming to 1.5°C'

It’s vague, with no requirement to measure or reduce. B Lab has chosen not to require SBTi-aligned targets and emissions data in an effort to reduce cost and pressure on smaller businesses. As a small business ourselves, we understand the sentiment! But low-burden, affordable ways to measure and act already exist, and minimal requirements risk undermining B Corp’s reputation as the benchmark for responsible business.

In practice, many SMEs already face stronger demands from customers, partners, investors, and employees when it comes to climate commitments. On this front, B Corp isn’t setting the bar – it’s catching up.

Recommendation – Even though it isn’t strictly required, measure your full Scope 1–3 footprint. It’s the only way to properly understand your emissions, prioritise reductions, and make your plans truly SMART (Specific, Measurable, Achievable, Relevant, Time-bound).

Large Company Requirements

Plain-English summary – From Year 0, Large companies must measure and publicly disclose a complete Scope 1–3 inventory every year and obtain independent third-party verification annually. By Year 3, adopt science-based targets and publish a Climate Transition Plan (check out an example here); consult on a just transition. From Year 5, act on just transition and disclose transition-plan progress annually.

Large requirements at a glance

Large B Corp Climate Action Requirements

A Note on Verification

Verification must be carried out by an organisation that is independent from whoever prepared your data. So, as your carbon accounting partner, Seedling can't be your verifier too (we'd be marking your own homework).

This means that large B Corps will have to engage another partner for verification of both emissions data. As it stands, the verifier will need to be accredited by a body that's an IAF member (e.g. UKAS, DAkkS, COFRAC, ENAC, RvA).

For targets, you need external sign-off: either SBTi validation or independent third-party verification that your targets meet 1.5°C science. Inventory assurance and target sign-off are separate obligations – you can use one firm for both if they’re accredited, or choose SBTi for targets.

The problem here is cost - UKAS-level accreditation is not cheap and as a result has to date level only been conducted by the largest organisations. So, whilst for Small and Medium businesses B Corp has reduced barriers, there is a risk that 'Large' B Corps may find themselves priced out of B Corp ceritifcation.

At Seedling, we're experts at getting your data and supporting evidence in the best possible place for third-party verification, without creating too much extra admin burden. We also team up with verification partners to keep the process streamlined.

Action checklists

Here's a summary checklist to help you get started.

Small & Medium – today → Year 3

Publish your Climate Action Plan with SMART targets, resourcing, stakeholder engagement and board approval
In year 3: Demonstrate and publish progress versus plan
Consider measuring emissions as a way to keep your progress measurable (and relevant!)

Large – today → Year 3 → Year 5

Follow an annual cycle: measure → disclose → independent verification
By Year 3: adopt science-based targets, publish a Transition Plan, complete just transition consultations
By Year 5: act on just transition and annually disclose Transition-Plan progress

How Seedling helps

The new standards can feel like a big leap, especially if you’re balancing day-to-day business alongside certification. Seedling makes it manageable.

We combine intuitive software with one-to-one expert support to help you:

Capture a complete, GHG Protocol–compliant Scope 1–3 footprint without drowning in spreadsheets.
Turn your data into a credible Climate Action or Transition Plan, with clear targets and a practical roadmap.
Stay on track for B Lab’s Year 0 → Year 3 → Year 5 milestones, so there are no surprises at recertification.

For Large companies, we also remove the headache of verification. We partner directly with accredited auditors – producing the evidence trails, exports and category-level justifications they need – so you don’t have to coordinate between multiple providers. That means one smooth cycle: measure → disclose → verify, repeated each year with confidence.

We already support 250+ businesses, including 30+ certified B Corps, to measure accurately, reduce emissions, and meet standards with confidence.

Ready to simplify B Corp Climate Action? Let’s chat about how Seedling can help your team prepare with confidence.

FAQs

Do Small & Medium companies have to measure emissions under v2.1?
No. Small & Medium must publish a Climate Action Plan at Year 0 and publish progress at Year 3. Measurement isn’t mandated, but it’s the most reliable way to demonstrate progress and answer customer due diligence.

What counts as public disclosure for CA1.1, CA3.6 and CA3.7?
A page on your corporate website or a report that’s accessible without paywalls or logins. Keep disclosures in a consistent location and update them on the Year 0 → Year 3 → Year 5 cadence.

What’s the difference between a Climate Action Plan and a Climate Transition Plan?
The Climate Action Plan sets commitments, SMART targets, resourcing and governance. The Climate Transition Plan is the operational roadmap that delivers science-based targets with clear roles and investment.

How is company size determined?
By number of workers or revenue, whichever is higher. Moving from Medium to Large changes what applies at Year 0.