Is Diag Décarbon'Action cheaper than a standard Bilan Carbone®?

1What the Diag is

Diag Décarbon'Action is a complete Bilan Carbone®, with no simplified version: it is carried out by an expert certified in Bilan Carbone® or an equivalent method, authorised by ADEME, Bpifrance and the ABC, using the Bilan Carbone® V9 method (July 2024), with scopes 1, 2 and 3, a quantified action plan and a strategic presentation of the results. The official specification provides for 12 days of work spread over 10 months. This is the deliverable you would receive from the same consultancy in a private engagement costing €15,000 excl. VAT.

The difference is in the funding. With a standard Bilan Carbone®, the company pays 100% of the bill. With a Diag, it pays 60% of a €10,000 excl. VAT fixed fee, and ADEME and Bpifrance fund the remaining 40% for identical work.

The State funds this first assessment because SME decarbonisation is part of national objectives (the National Low-Carbon Strategy, the Paris Agreement) and many business leaders do not take the step at €15,000 excl. VAT. By lowering the entry cost to €6,000 excl. VAT, the programme brings in companies every year that would otherwise have stayed away.

2The figures to know

The ranges observed in the French market in 2026:

• Standard Bilan Carbone®, single-site SME, independent certified consultancy: €11,000 to €18,000 excl. VAT, depending on complexity
• Diag Décarbon'Action: €6,000 excl. VAT payable by the company, with the public programme funding 40% of a €10,000 excl. VAT fixed fee
• Bilan Carbone® from a large Paris consultancy: €25,000 to €40,000 excl. VAT, generally outside the Diag, whose fixed fee is set at €10,000 excl. VAT

For an industrial SME with 80 employees, the net difference is close to €10,000 excl. VAT for an equivalent service, and this is often what persuades management to start its assessment now rather than postpone it for a year.

3The 4 conditions to check

To qualify for Diag Décarbon'Action, you must meet 4 criteria.

• A company with fewer than 500 employees, including micro-enterprises, based in France or an overseas territory. Above that, the programme does not apply
• At least 1 year in business, so that the assessment covers a complete year
• No GHG inventory carried out in the last 5 years: the Diag is designed for a first assessment
• An expert approved by Bpifrance and certified in Bilan Carbone® or an equivalent method. Not every consultancy is on the list: check before signing

If any of these criteria excludes you from the programme, a standard Bilan Carbone® remains well justified, and other grants to reduce the cost of your assessment exist (regional grants, sector funds), although they are less generous than the Diag.

4What to know before signing

The programme depends on public funding. The official page lists it as available in 2026, with no application deadline, but the budget may run out or be revised: it is better not to delay your decision. Last year, we saw 2 SMEs miss out on the grant after 15 days of hesitation in the spring: each lost €4,000 in subsidy because the funding allocation had run out between 2 quotes.

The specification is precise. This is reassuring for quality, but a consultancy offering a "bespoke Diag outside the framework" is selling you something different from what the programme provides. Before signing, ask for the name of the approved expert and check that the engagement is being arranged through Bpifrance.

For invoicing, Bpifrance pays the consultancy for the publicly funded share, with an administrative lead time of 2 to 3 months after the engagement ends. Nothing changes for you: you pay your share at the start or on delivery, depending on the consultancy.

5Where to start

Start by checking your eligibility against the Bpifrance criteria: fewer than 500 employees, 1 year in business, no GHG inventory for 5 years. Then request a Diag-format quote from 2 or 3 consultancies approved by Bpifrance and certified in Bilan Carbone®, and sign without delay.

For an eligible SME, the difference from a full-price Bilan Carbone® is close to €10,000 excl. VAT. The programme is generous and its conditions are clear: you still need to choose who will prepare the application and set a signing date.

Further resources

Frequently asked questions

1What is the difference between Diag Décarbon'Action and a standard Bilan Carbone®?

The deliverable is the same: a complete Bilan Carbone®, covering scopes 1, 2 and 3, with a quantified action plan and a presentation of the results, carried out by a certified consultancy. The difference is in the funding: under the Diag, ADEME and Bpifrance pay part of the bill directly to the consultancy, and the company's share falls to around €6,000 excl. VAT, versus €10,000 to €30,000 excl. VAT for a standard assessment, depending on complexity. In return, the Diag is restricted to French companies with fewer than 500 employees and no GHG inventory in the last 5 years, requires an approved consultancy and depends on public funding.

2What is the final cost of a Diag Décarbon'Action and a standard Bilan Carbone®?

A standard Bilan Carbone® carried out by an independent certified consultancy costs €11,000 to €18,000 excl. VAT for a single-site SME, and €25,000 to €40,000 excl. VAT through a large Paris consultancy. With Diag Décarbon'Action, the company pays around €6,000 excl. VAT for an equivalent service, with the public share paid directly to the consultancy. For an industrial SME with 80 employees, the net difference is close to €10,000 excl. VAT. Large consultancies generally remain outside the Diag because the programme caps the eligible fee.

3When should you choose Diag Décarbon'Action?

Whenever your company is eligible: a French company with fewer than 500 employees, including micro-enterprises, with at least 1 year in business, which has neither participated in the programme nor carried out a GHG inventory in the last 5 years, and is ready to work with a consultancy approved by Bpifrance and certified in Bilan Carbone®. It is then the cheapest route to a complete Bilan Carbone®, with the company paying around €6,000 excl. VAT. As the Diag cannot be repeated, define the scope of this first engagement carefully.

4When should you choose a standard Bilan Carbone®?

When you are not eligible for Diag Décarbon'Action: more than 500 employees, less than a year in business, a GHG inventory carried out in the last 5 years or a non-French company. This also applies if you want to work with a consultancy that is not approved by Bpifrance, which generally includes large consultancies. A standard assessment then remains well justified, at €11,000 to €18,000 excl. VAT for a single-site SME, and other grants exist, particularly regional or sector grants, although they are less substantial than the Diag.

Ask Guillaume your questionA personal reply within 24 working hours

Send my questionor: [email protected]