- 1Recommended in the BEGES of most private companies, scope 3 is mandatory there for public entities and companies required to produce a sustainability statement (CSRD).
- 2Scope 3 accounts for 88% of emissions on average, and SBTi requires large companies to set a target for it.
- 33 direct consequences of an assessment without scope 3: a lost tender, decisions made blindly, costly catch-up work.
- 4CSRD, BEGES, clients: market pressure makes it a de facto requirement.
- Is scope 3 mandatory in a Bilan Carbone®?
Yes in the public sector, virtually mandatory in the private sector.
- For the public sector: mandatory since the 2022 decree.
- For the private sector: recommended by law (mandatory under the CSRD) and often required by customers and funders.
- Without scope 3, you measure only 12% of your actual footprint on average.
1What the law says, precisely
The French regulations on BEGES were revised in 2022 by Decree No 2022-982. There are 2 statuses to distinguish, which are not treated in the same way.
No box really says "no"
Sector × regime comparison - what the law says versus what practice requires.
For legal entities governed by public law, the State, regions, departments, municipalities with more than 50,000 inhabitants, EPCI and public establishments with more than 250 staff, scope 3 is included in the mandatory coverage. Local authorities and public services must now cover scope 1, scope 2 and scope 3.
For private companies subject to BEGES (more than 500 employees in metropolitan France, more than 250 in overseas territories) that are not required to publish a sustainability statement, scope 3 remains "recommended but not strictly required". A company publishing its BEGES for scopes 1 and 2 only complies with the regulations. Its only obligation is to explain in the report how scope 3 was handled, including if it was excluded: omission thus becomes an explicit, visible decision rather than a silent oversight.
In practice, companies subject to the DPEF (non-financial performance statement, which applied to large companies before the CSRD) already addressed scope 3: the 2022 decree made it mandatory in their BEGES from 2023, and their investors and auditors requested it. Since the Omnibus I Directive, the CSRD covers only companies with more than 1,000 employees and turnover of more than €450 million. It requires scope 3 whenever it is "material", meaning significant in the total, which is the case almost everywhere.
Add the SBTi (Science Based Targets initiative, the international reference for aligning reduction targets with the Paris Agreement). It requires large companies to set a scope 3 reduction target: currently whenever it exceeds 40% of total emissions and, in version 2 of its net-zero standard published in June 2026, for all categories accounting for at least 5% of scope 3. For most SMEs, this target is optional, but measuring scope 3 remains essential to make the trajectory credible.
Overall, the legal requirement remains limited, but European regulations, investors and clients mean most companies end up having to measure scope 3.
2What reality says
Even before the regulatory question, there is a question of purpose. A Bilan Carbone® without scope 3 leaves out scope 3, or an average of 88% of emissions. Above all, it misses what justifies a Bilan Carbone®: decarbonising the activity, rather than merely measuring direct consumption.
An assessment without scope 3 measures only 12% of emissions on average
Average emissions breakdown of a European company (tertiary sector, industry, services).
Beyond this principle, publishing an assessment without scope 3 has 3 direct consequences.
Clients reject the assessment. Large companies managing their own scope 3 ask suppliers for assessments that include it. An assessment without scope 3 comes back marked "insufficient for inclusion in our reporting", which can disqualify a supplier from a demanding tender.
The assessment is useless internally. When scopes 1 and 2 account for only 12% of emissions, an assessment restricted to these scopes produces a figure unrelated to the real issue. If your "official" emissions are 400 tCO2e per year while scope 3 contains 3,000, you comply with the rules but have no visibility of decarbonisation levers.
Catch-up work is expensive. A company publishing a scope 1 + 2 BEGES in 2026 and asked for scope 3 in 2027 by a client must repeat a full assignment, this time with real data collection (purchases, freight, travel, capital goods, end of life). Overall, this often costs more than a full assessment completed in one go. We encountered an industrial mid-cap that published a scope 1+2 BEGES for €9,000 excluding VAT in 2023 to "do the minimum"; its first major automotive client requested a full assessment with detailed scope 3 category 1 (purchases) at the end of 2024. The catch-up assignment cost €17,000 excluding VAT, with a 4-month delay during which the sales process remained blocked. Total over 18 months: €26,000 excluding VAT and a €1.2 million order put at risk. A full initial assessment would have cost €14,000 excluding VAT.
3The 3 cases where leaving out scope 3 is defensible
There are nevertheless situations where an assessment without scope 3 remains reasonable.
The first assessment of a micro-business with fewer than 10 employees, when the main aim is internal awareness and scope 3 can be quickly approximated using monetary ratios without compromising the assessment's use.
A public organisation under severe budget constraints that cannot fund a full assessment and simply needs to publish its BEGES. Many small local authorities are in this situation: scope 1 + 2 is a first step, better than nothing.
A targeted energy diagnosis, which is not a Bilan Carbone® but a narrower audit. In this case, we are no longer talking about a Bilan Carbone®, but about something else, and the scope 3 requirement does not apply.
Outside these situations, an assessment without scope 3 is a short-term calculation that costs more over time.
4What this changes on the invoice
A scope 1 + 2-only assessment costs around €4,000 to €7,000 excluding VAT for an SME, compared with €10,000 to €30,000 excluding VAT for a full assessment with scope 3 handled using physical data. The difference seems to justify the temptation to save; we detail the actual ranges in our Bilan Carbone® cost guide.
But the assessment's cost is not the only cost to consider. A scope 1 + 2 assessment reused in a lost tender means several hundred thousand euros in turnover lost. A scope 1 + 2 assessment that must be redone as scope 1 + 2 + 3 the following year means a second invoice and 6 more months of work. Relative to the value created or preserved, saving on scope 3 in the first assessment almost always costs more in the following 18 to 24 months, and we see several smarter ways to save than cutting scope 3.
5What changes by 2028
The pressure nevertheless continues. The Omnibus I Directive refocused the CSRD on companies with more than 1,000 employees and turnover of more than €450 million, which must still document scope 3 in their value chain. From the 2027 financial years, once Omnibus is transposed, they will be able to require from suppliers with no more than 1,000 employees only the information provided for by the voluntary standard derived from the VSME, but will continue to request carbon data.
Scope 3 remains optional in the legal texts for most companies, but is increasingly required in practice. A company carrying out a first assessment without scope 3 in 2026 will very probably have to repeat it with scope 3 between 2027 and 2029, meaning 2 assignments instead of one and a higher total invoice.
6Scope 3 from the first assessment, in most cases
Today, the pressure comes mainly from clients and investors, more than from legal texts. For a company serving major accounts, seeking B Corp certification, preparing an SBTi trajectory or coming within the CSRD, the question of including scope 3 no longer arises. The remaining choice is the level of detail, monetary ratios or physical data, according to the materiality of each category. Economically, the right horizon is 18 to 36 months: a full initial assessment almost always costs less than an imposed update within 2 years.
Before signing a quote, check Diag Décarbon'Action eligibility and compare the total cost over 3 years rather than the headline price of the first assessment.
