The 5 most common mistakes to avoid when obtaining MITECO's carbon footprint certification

Many companies reach the final stage of the carbon footprint certification process run by Spain's Ministry for the Ecological Transition and the Demographic Challenge (MITECO) convinced they have done everything right, only to receive a formal request that forces them to start again from almost zero.

The MITECO carbon footprint registry is not especially complex in concept (you measure your emissions, define a reduction plan and submit the documentation), but in practice it is full of points where organisations make mistakes that, if not caught in time, stretch the process out for months or block the application altogether. For a complete overview of the procedure, see our guide to the MITECO registry and the Calculate, Reduce and Offset seals.

In this article we set out the five most frequent mistakes we see in companies trying to register with MITECO, and how to avoid them from the very first step.

Mistake 1: defining organisational boundaries poorly

The first mistake, and the one with the biggest knock-on effects, is failing to spend enough time correctly defining what your organisation includes for the purposes of the calculation.

Organisational boundaries determine which sites, subsidiaries and activities fall within your emissions inventory. If this definition is vague, incomplete or inconsistent with the reality of your business, everything that follows (data collection, the calculation, the documentation) will be built on a flawed foundation.

Common problems include:

• Including sites in other countries when, since 2026, MITECO only registers emissions within Spanish territory.
• Excluding relevant emission sources (those representing 5% or more of the total) without methodological justification.
• Not being clear about the distinction between different legal entities within the same corporate group.

How to avoid it: before you start gathering data, document in writing what your organisation includes and excludes, and why. That document will form part of the descriptive report you have to submit to MITECO.

Mistake 2: working with unreliable activity data or no supporting documentation

An emissions calculation is only as good as the data feeding it. And this is where many companies hit their first major hurdle: gathering real, verifiable data backed by documentation.

An approximate estimate of natural gas consumption or a round figure for fleet mileage is not enough. MITECO can request evidence for any reported figure: energy bills, contracts, consumption records, delivery notes and so on.

The most typical mistakes at this stage:

• Using estimated data when real data is available (invoices, meters, etc.).
• Having no records of refrigerant gases or of fuel used in company vehicles.
• Collecting data in a scattered way (in emails, loose spreadsheets, files held by different departments) with no central system, which makes it impossible to audit the information afterwards.

How to avoid it: set up a single data collection system with clear traceability from the outset. Every data point needs a source, a date and a supporting document. Since you will repeat the process every year, this system will save you weeks of work.

Mistake 3: applying an incorrect methodology or unrecognised emission factors

MITECO requires the calculation to follow recognised methodologies and the emission factors used to be the official ones. This is not negotiable.

Even so, it is common to find inventories built with generic emission factors taken from international sources (IPCC, DEFRA or other European databases) when MITECO requires, for certain sources, the specific factors published by the Ministry itself. It is also common for companies to be unable to justify how they reached each result, which causes problems during the review.

One particular case: if your organisation carries out agricultural activities directly, you are required to use MITECO's official calculators or to have the calculations verified by an independent third party.

How to avoid it: before you begin, check which emission factors you must use for each scope and category, and document the source of each one. Do not take any factor as valid without confirming it is aligned with MITECO's requirements for the reporting year you are declaring.

Mistake 4: leaving out the reduction plan or submitting it without the required content

One of the most underrated requirements in the registration process is the emissions reduction plan. Many companies reach the documentation phase without having worked on it, or they put it together superficially, assuming anything will do.

It will not. The reduction plan is mandatory to register with the "Reduce" seal, and it must include:

• Concrete reduction measures (not generic statements of intent).
• An estimate of the expected impact of each measure in tonnes of CO₂e.
• A time horizon and an implementation schedule.

Without these three elements, the plan does not meet the requirements and can trigger a formal request or a rejection of the application.

How to avoid it: the reduction plan is not the final step of the process but an integral part of it. Identify your main emission sources right from the start of the calculation and model which reduction measures are feasible for your organisation. That lets you build a plan grounded in your own data, not in good intentions.

Mistake 5: submitting incomplete, inconsistent or poorly structured documentation

This is, by far, the point where most applications get blocked. Not because of calculation errors, but because of problems with the documentation.

The file you submit to MITECO includes several documents that have to be consistent with one another: the application form, the descriptive report on the organisation and its footprint, the summary of Scope 1 and 2 calculations, the reduction plan and, where applicable, the Guarantees of Origin document for renewable electricity. If the figures do not match across documents, if the description of the organisational boundaries does not line up with what is declared in the calculations, or if a required document is missing, the application will stall.

Other frequent mistakes at this stage:

• Not including the monitoring report when it is not the first year of registration.
• Trying to apply for the "Calculate + Reduce" seal without preparing the corresponding responsible declaration.
• Submitting documentation that is not aligned with the registry's current requirements, which changed with Royal Decree 214/2025.

How to avoid it: review every document before submitting the application to make sure the data is consistent throughout. Treat the file as a whole, not as a set of independent documents.

In summary: the challenge is not measuring, it is getting it right from the start

Earning the MITECO seal does not have to be a headache. The five mistakes above boil down to three pillars that, once resolved, turn registration into a simple formality:

1. Clear definition: what you measure and why (organisational boundaries and the correct methodology).
2. Real data: no rough estimates, with documentary backing.
3. Consistency: all your documents, including the reduction plan, say the same thing.

If you want to leave manual processes behind when obtaining your certification, you can manage the entire registration with Manglai's carbon footprint platform, integrated with MITECO.