To obtain an auditable carbon footprint report in Spain you need three things: calculate emissions in line with ISO 14064-1:2018 or the GHG Protocol, have them verified by a body accredited by ENAC under UNE-EN ISO/IEC 17029 and UNE-EN ISO 14065, and keep every figure traceable back to its source document.
That verified report is what public contracting authorities, customers reporting Scope 3 and financial institutions accept. Registration in the MITECO carbon footprint registry is voluntary for private companies, but it is what adds the official Calculo, Reduzco or Compenso seal.
What is carbon footprint certification and how does it differ from verification?
The two words are used interchangeably, but they are not the same. Verification is the process by which an independent body reviews an emissions inventory that has already been calculated and issues a statement on whether the information is complete, accurate and consistent with the declared criteria. Certification is the commercial term normally used for the outcome: the document you can show to a third party.
Greenhouse gas verification follows ISO 14064-3, which defines two levels of assurance, limited and reasonable, and requires a materiality threshold to be set. A reasonable assurance report is more demanding and more expensive, and it is the one usually requested by customers consolidating your figure into their own Scope 3.
Before verifying, you have to calculate properly. To review the method, the formula and the official factor sources, see our guide on what a carbon footprint is and how to calculate it.
What exactly does ENAC accredit?
The Spanish National Accreditation Entity (ENAC) does not verify carbon footprints. What it does is accredit the bodies that do, periodically checking their technical competence, impartiality and the consistency of their procedures. It is the same organisation that accredits laboratories and inspection bodies in Spain.
For environmental validation and verification, ENAC works with two reference standards:
- UNE-EN ISO/IEC 17029: general competence and consistency requirements for any validation and verification body.
- UNE-EN ISO 14065: specific requirements for bodies validating or verifying greenhouse gas information.
Within that framework, ENAC covers schemes such as organisational carbon footprints, the EU Emissions Trading System, the Carbon Border Adjustment Mechanism (CBAM, Regulation (EU) 2023/956), which explicitly requires verifiers accredited by a national accreditation body, and sustainable aviation fuels under Regulation (EU) 2023/2405.
An ENAC accreditation is what turns a verifier's statement into a document recognised outside your own company. ENAC publishes the list of accredited bodies and their scope at enac.es, and it is worth checking before you sign: accreditation is granted per scheme, not generically.
What do I need to present a carbon footprint in a public tender?
Article 202 of Spain's Public Sector Contracts Act (Ley 9/2017) requires every tender document to include at least one special performance condition, and it explicitly lists reducing greenhouse gas emissions among the environmental options. Article 145 also allows environmental characteristics to be used as an award criterion.
In practice: more and more tenders ask you to evidence your footprint or its reduction, each with slightly different wording. What usually covers almost all of them:
- A Scope 1 and 2 carbon footprint report for the last closed financial year, calculated with a recognised standard.
- A verification statement issued by an ENAC-accredited body, stating the assurance level and the year covered.
- A reduction plan with a quantified target and a base year, as required by RD 214/2025.
- Where the tender explicitly mentions the national registry, registration with the Calculo seal or, if demonstrated reduction is required, the Reduzco seal.
A common mistake is submitting a management system certificate, such as ISO 14001, assuming it will do. It will not: it certifies the system, not the emissions figure. There are more cases like this in our list of common mistakes when certifying a carbon footprint with MITECO.
What does each stakeholder ask for?
| Stakeholder | What they usually ask for | Document that solves it |
|---|---|---|
| Public contracting authority | Evidence of emissions or their reduction as a special performance condition (art. 202 LCSP) or award criterion (art. 145 LCSP) | Verified report for the last financial year and, if the tender cites it, registration with the Calculo or Reduzco seal |
| Corporate customer reporting Scope 3 | Emissions attached to the product or service they buy, with method, year and declared factors | Verified ISO 14064-1 inventory plus a breakdown per unit of product or service |
| Bank or financial institution | Data for their financed emissions and their own sustainability reporting | Verified Scope 1 and 2 footprint plus a reduction plan with a quantified target |
| Sustainability or financial auditor | Data traceability and evidence behind the calculation | Working papers, source documents and a factor log with source, version and year |
| MITECO registry | Scopes 1 and 2 as a minimum, using the registry's own factors | Verified report, except for the cases in article 6.6 of RD 214/2025 |
Does RD 214/2025 require carbon footprint certification?
Not exactly, and this is the most widespread confusion. Royal Decree 214/2025 requires companies to calculate their Scope 1 and 2 footprint, publish it free of charge and accessibly on their corporate website, and draw up a reduction plan with a quantified target over a minimum five-year horizon. It applies to companies that already prepare the non-financial information statement: more than 250 employees plus either public-interest entity status or exceeding, over two consecutive financial years, 20 million euros in assets or 40 million euros in turnover. MITECO has clarified that publication must happen within six months of the financial year end, in line with the non-financial statement timetable.
What the royal decree does not do is force every company to register or to verify:
- Registration is voluntary for private companies. It is mandatory only for the state public sector, from 2026, and with Scope 3 from the 2028 calculation onwards.
- If you meet the obligation without registering, using the published emission factors is enough.
- If you do register in section a) of the registry, article 6.6 requires independent third-party verification, unless you are an SME, association, foundation, cooperative or public administration and all your significant emissions have a factor published by the Spanish Climate Change Office. To include Scope 3, verification is required except for small and micro enterprises with available factors, and for large events it is always mandatory.
Article 6.6 also recognises, alongside bodies accredited to verify GHG under ISO 14064 or the GHG Protocol, Kyoto Protocol designated operational entities and reports issued under ISAE 3410.
What seals exist in the MITECO registry?
| Seal | What it evidences | What you have to provide |
|---|---|---|
| Calculo | That the organisation has calculated its Scope 1 and 2 footprint | The year's footprint using registry factors, a reduction plan and a verification report except in the listed cases |
| Reduzco | That it has reduced its footprint over time | Four consecutive years of data to compare two overlapping three-year periods, with the recent period's average ratio below the earlier one |
| Compenso | That it has offset part or all of its emissions | Quantified tonnes and removals purchased from projects registered in section b) of the registry, located in Spain |
The full requirements and deadlines for each are in our guide to the Calculo, Reduzco and Compenso seals, and the concrete return of being registered is covered in the benefits of registering your carbon footprint with MITECO.
How do you obtain an auditable report, step by step?
- Define boundaries and period. Which legal entities and sites are in, under which consolidation approach, and which twelve months are analysed.
- Choose the standard. ISO 14064-1:2018 if you need a certifiable report; the GHG Protocol if your customer or investor works in scopes.
- Calculate with official factors. For the Spanish registry, MITECO's factors, and the electricity mix published by the CNMC for each supplier.
- Prepare the evidence. Invoices, meter readings, waste transfer notes, refuelling records, fluorinated gas logs and a spreadsheet with visible formulas.
- Engage an ENAC-accredited verifier whose accreditation scope specifically covers carbon footprints. Check the scope, not just the fact of accreditation.
- Pass the audit. Document review, interviews, data sampling and, where applicable, a site visit. Non-conformities are raised and there is a window to close them.
- Receive the verification statement with the assurance level, the materiality applied, the period covered and any exclusions.
- Register with MITECO if you need to and attach the carbon footprint reduction plan that section a) requires.
What does the verifier check, and where do companies usually fail?
- Inventory completeness: a missing site, a standby generator or refrigerant top-ups left out.
- Traceability: a figure in the spreadsheet with no invoice or meter reading behind it.
- Factor consistency: mixing factors from different years, or using another country's factor without justifying it.
- Cut-off: invoices spanning two financial years allocated to the wrong one.
- Base year changes: restructurings or acquisitions that require recalculating the baseline and are not documented.
- Justifying exclusions: dropping a source as insignificant without quantifying why.
What is a certified footprint actually good for?
- Access to contracts: meets the environmental criteria and conditions of public tenders and large-customer vendor approval processes.
- Supply chain: gives customers consolidating your footprint into their Scope 3 an acceptable figure, without redoing the calculation each time.
- Financing: gives banks and investors the metric they need for financed emissions and their own reporting.
- Protection against greenwashing: a figure verified by an accredited third party supports what you communicate.
- Internal efficiency: the process surfaces mis-recorded consumption, duplicate contracts and energy inefficiencies.
Frequently asked questions about carbon footprint certification
Is registration with MITECO mandatory?
Not for private companies: registration is voluntary. It is mandatory for state public sector entities from 2026. What is mandatory for companies within the scope of RD 214/2025 is calculating the footprint, publishing it and having a reduction plan.
Can an SME register without external verification?
Yes, if all its significant Scope 1 and 2 emissions have a factor published by the Spanish Climate Change Office. If it includes Scope 3 or sources without a published factor, verification is required.
How long is a verification report valid?
It covers a specific period, normally one financial year. It does not expire, but it stops being useful as soon as the other party asks for the following year, so in practice the cycle is annual.
Do ISO 14001 or EMAS count as carbon footprint certification?
They do not replace it. They certify an environmental management system, not the emissions figure. RD 214/2025 does accept supplementary information from schemes such as EMAS or ISO 50001, but the document that evidences the footprint is the verification statement.
What is the difference between limited and reasonable assurance?
Limited assurance concludes that nothing has been found to suggest material error; reasonable assurance positively states that the information is correct within the materiality set. Reasonable assurance requires more sampling and more evidence.
What if my verifier is not accredited by ENAC?
The report may be technically sound, but a tender or a registry that requires accreditation will reject it. Always check the verifier's accreditation scope before engaging them.
At Manglai we calculate footprints under the GHG Protocol and ISO 14064, with every figure traceable back to its source invoice, which is exactly what a verifier asks for. If your goal is registering with the national registry, see Manglai's solution for the MITECO registry; if you need a certifiable inventory, see the ISO 14064 solution.
