Most companies buy their first carbon credits after a sales call and a quote. The quote shows a price per tonne and a project photo. What it rarely shows is whether the credits will hold up when an auditor, a journalist or a customer asks how you chose them.
The fix is simple and underused: send every supplier the same list of carbon credit supplier questions and ask for written answers. Written answers make offers comparable, expose the suppliers who avoid specifics, and leave you with an audit trail for CSRD reporting and for any claim you make about the purchase.
The 19 questions below are the ones in Regreener’s free RFP builder. Most of them are based on public frameworks: the ICVCM Core Carbon Principles, the Carbon Credit Quality Initiative (CCQI), the Symbiosis Coalition quality standard for nature-based removals and the Oxford Offsetting Principles; the rest is buying practice. For each question you get the wording to send, what a good answer looks like and the red flags.
The short answer. Ask about integrity (11 questions), social and environmental safeguards (3) and delivery and the supplier (5). Treat the integrity basics as yes-or-no minimum requirements, score the rest from 0 to 5, and compare price only between offers that pass the minimums.
How to use these questions
Send the questions as one written questionnaire with a deadline, and ask every supplier to answer all of them for each project they offer. Three practical rules:
Same questions, same format. Answers you can put side by side are worth more than any presentation.
Minimums first. Decide which questions are pass-or-fail for you, for example a public registry, retirement in your name and no double counting. An offer that fails a minimum is out, whatever the price.
Ask for evidence. A registry link, a verification report or a letter of authorisation says more than “high quality” or “fully verified”.
Some questions only apply to removals or to nature-based projects. They are marked below.
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Integrity: is the tonne real, and is it yours?
1. Is the programme CCP-Eligible?
Ask: “Are the credits issued under a programme assessed as CCP-Eligible by the ICVCM? Name the programme.”
Good answer: a named programme on the ICVCM list. On 4 August 2026 the ICVCM assessment status page listed 13 CCP-Eligible programmes and 45 CCP-Approved methodologies; check the current list on the day you evaluate.
Red flag: “we use our own standard” or an answer that names a registry but not a programme.
2. Is the methodology CCP-Approved?
Ask: “Is the methodology, in the version used for these credits, CCP-Approved by the ICVCM, and are the credits tagged with the CCP label in the registry? Name the methodology and version.”
Good answer: methodology name and version, and confirmation that the credits carry the CCP label in the registry. A CCP-Eligible programme alone is not enough; the label needs both. Our overview of CCP-labelled carbon credits shows what this looks like in practice.
Red flag: an older methodology version that was not approved, presented as if the label applied.
3. Where is it registered, and who verified it?
Ask: “Are the credits issued on a public registry with unique serial numbers, and verified by an independent validation and verification body accredited for this programme? Name the registry, the project ID and the verifier, and link the latest verification report.”
Good answer: a registry link to the project page, the verifier’s name and a recent verification report.
Red flag: no project ID, or a verification report that is years old for a project still issuing credits.
4. How is additionality shown?
Ask: “How does the project show it would not happen without carbon revenue? Name the additionality test used and confirm the activity is not required by law.”
Good answer: the specific test (investment, barrier or common-practice analysis, or a performance benchmark) and why the project passes it.
Red flag: “the project is additional” with no test named, or a project type that is already profitable without carbon revenue.
5. How conservative is the quantification?
Ask: “Describe the baseline and how often it is updated, how leakage is accounted for, and which uncertainty deductions apply. Explain how the monitoring data are collected.”
Good answer: a baseline that is reassessed over time, a leakage deduction, uncertainty deductions and monitoring that uses measured data, not only modelled assumptions.
Red flag: a fixed historical baseline for a forest project and no mention of leakage. Over-crediting usually starts here.
6. What happens if the carbon is released again? (removals)
Ask: “Are reversals monitored and compensated through a buffer pool, replacement or insurance? Describe the mechanism, how long monitoring lasts and who is responsible if a reversal happens.”
Good answer: a named buffer pool or replacement obligation, a monitoring period, and a clear party responsible for compensation.
Red flag: “the risk is very low” instead of a mechanism.
7. Where is the carbon stored, and for how long? (removals)
Ask: “Where is the carbon stored, for example in trees, soils, biochar, minerals or geological formations, and how long is it expected to stay stored? Give the evidence for that duration.”
Good answer: a storage type and a duration with evidence. This matters for SBTi: from 2035, Category A companies need a growing share of long-lived removals, carbon stored for centuries to millennia.
Red flag: a durability claim of “permanent” for storage that depends on land use.
8. Will the credits be retired in our name?
Ask: “Will you retire the credits in our name as the beneficiary, and send the serial numbers and a link to the public retirement record within 30 days of each retirement?”
Good answer: yes, with a sample retirement record.
Red flag: retirement “on behalf of our clients” in a pooled account. You cannot prove which tonnes are yours.
9. Is double counting excluded?
Ask: “Can you confirm the credits are issued on one registry only, and are not sold, retired or claimed by anyone else, including under another programme or a compliance scheme?”
Good answer: a written confirmation, ideally as a contract clause.
Red flag: hesitation about whether the same project also issues under a national scheme.
10. What is the Article 6 status?
Ask: “Has the host country authorised the credits under Article 6 of the Paris Agreement, and for which use? Will a corresponding adjustment be applied? Provide the letter of authorisation if available.”
Good answer: a clear yes or no, and the letter of authorisation if there is one. Neither answer disqualifies a project for voluntary use, but you need to know which one you are buying. Under SBTi V2, companies must report this for removals used to neutralise residual emissions.
Red flag: “corresponding adjustments are not relevant for us”, without explanation.
11. Is the project rated or criticised?
Ask: “List any independent ratings of the project (provider, rating and date), and any public reviews, media reports or criticism you are aware of.”
Good answer: ratings with dates, and an honest mention of known criticism with the supplier’s view. Our comparison of carbon credit rating agencies explains what each rating measures.
Red flag: “no issues” for a project type that has been widely criticised. A quick search on the project name often tells you more.
Social and environmental: who carries the cost?
12. Are safeguards and rights in place?
Ask: “Does the project apply social and environmental safeguards, have a working grievance mechanism and clear land and carbon rights? Describe how local communities and Indigenous Peoples were consulted, including free, prior and informed consent where it applies.”
Good answer: a named safeguards policy, a grievance mechanism people can actually reach, and documented consent.
Red flag: unclear land tenure or carbon rights. That is a legal risk as much as an ethical one.
13. How much revenue reaches local communities?
Ask: “Which share of the credit revenue reaches local communities, and how? Is the benefit-sharing arrangement published? Which co-benefits are certified, and under which standard?”
Good answer: a share or amount, a published benefit-sharing arrangement and certified co-benefits.
Red flag: co-benefits that are claimed in marketing material but not certified anywhere.
14. Is the design right for the ecosystem? (nature-based)
Ask: “Which species and designs are used, how are they suited to the local ecosystem, and how does the project avoid monocultures and the conversion of natural ecosystems?”
Good answer: native or suitable species, mixed planting, and evidence that no natural ecosystem was converted.
Red flag: fast-growing monoculture plantations sold as restoration.
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Delivery and supplier: will you actually get what you pay for?
15. What if delivery fails or credits are invalidated?
Ask: “Do you offer a remedy, for example replacement with credits of equal quality or a refund, if delivery fails or credits are later invalidated? Are the credits already issued? If not, give the expected issuance and delivery schedule.”
Good answer: a contractual remedy and, for future credits, a delivery schedule. For forward purchases and offtakes, the remedy clause is often the most important part of the contract.
Red flag: future credits sold as if they were already issued.
16. Which vintages are offered?
Ask: “Is the vintage, the year the reduction or removal took place, of each batch no older than [your limit] years before the delivery year? List the vintages in the price sheet.”
Good answer: vintages per batch, within the limit you set. Choose a limit that fits your claims policy, for example five years before the delivery year. Our guide to carbon credit vintages helps you choose one.
Red flag: an attractive price on old vintages that is only revealed after you ask.
17. What is the price per tonne, and what are the fees?
Ask: “Give prices per tonne excluding VAT, with any fees shown separately. For deliveries over several years, state whether prices are fixed or indexed, and how.”
Good answer: a price per tonne per project and vintage, fees on a separate line, and a clear indexation rule for multi-year deals.
Red flag: an all-in package price that hides the margin. Prices that are far below the market for the same credit type deserve a second look; we explain why in why cheap carbon credits are a risk.
18. What is your role, and what have you delivered?
Ask: “What is your role (project developer, project owner, reseller or broker), and do you hold the credits, or a contract for them, today? Which volumes have you delivered recently? Give two buyer references.”
Good answer: a clear role, credits held or contracted, and references you can call.
Red flag: a reseller that does not hold the credits yet and cannot name the project owner.
19. What documentation do you provide for claims and reporting?
Ask: “Which documentation do you provide for our communication and reporting, for example retirement certificates, a project summary, and data on credit type, programme, vintage and corresponding adjustment?”
Good answer: a standard documentation pack. Since 27 September 2026 this matters more, because EU rules ban “carbon neutral” claims based on credits and every remaining claim has to be specific and verifiable. Our guide to carbon neutral claims under EmpCo explains what you can still say.
Red flag: a certificate that says “carbon neutral” or “climate neutral”. That is wording you can no longer use towards consumers.
How to score the answers
Separate the minimum requirements from the scored questions. Minimums are yes or no: an offer either has a public registry and retirement in your name, or it is out. Score the remaining questions from 0 to 5, where 0 means not addressed and 5 means clearly exceeds the requirement with good evidence.
Then weigh price against quality. The RFP builder starts from 30% price, 40% integrity and impact, 15% social and environmental, and 15% delivery and supplier, with the lowest average price getting full price points. Adjust the weights to your own priorities, but decide them before you open the offers. Our carbon credit tender guide covers the rest of the process, from timeline to award.
Tip from Bernard de Wit, Co-founder of Regreener: “The answers matter, but how suppliers answer matters too. In our experience the strongest suppliers send registry links and reports within days. The weakest send a brochure and a phone number. If a supplier cannot answer question 8 or 9 in writing, you have your answer.”
For forward purchases and offtakes, add the questions in our carbon offtake due diligence checklist, which covers the project developer’s finances and the contract terms that protect a multi-year deal. The RMI and Beyond Alliance Template for Carbon Credit Procurement is another useful public reference for standardised questions.
Get the questionnaire as a ready draft
You can copy the questions above into your own document. Regreener’s free RFP builder does it for you: answer a few questions about your purchase and you get a Word draft of your tender with these questions as a response form, plus an Excel sheet to score supplier answers side by side. It is a starting draft: you add your own terms and process.
If you would rather have the evaluation done for you, Regreener assesses every project against our 100+ datapoint quality framework before we offer it. Talk to a Climate Strategist about your next purchase.
