You can tell whether a travel-benefit provider's impact report is usable in your disclosure without auditing a single solar panel. Look at whether it presents a net number. If it subtracts the good thing it funded from the travel it sold you, it is not in a form you can report, and that is true even when every project behind it is real.
The rule that decides this is one sentence long, and it is already in the standard your inventory follows. Two more questions after it and you have a ten-minute test you can run on any vendor PDF.
The GHG Protocol's boundary rule
The Greenhouse Gas Protocol's Corporate Value Chain (Scope 3) standard sets out what a conformant report must contain. On each category, it requires total emissions in tonnes of CO2 equivalent, excluding biogenic CO2, and "independent of any GHG trades, such as purchases, sales, or transfers of offsets or allowances."
Independent of. Not net of. Your business travel figure is what your travel emitted, and it does not move because someone bought an instrument.
Chapter 9 says the same thing from the target side: keep "internal emissions in separate accounts from offsets used to meet the target, rather than providing a net figure," and any purchases or sales of offsets "are required to be reported separately."
Where the vendor's number does belong
The optional-reporting list is where the vendor's number belongs, and the standard's own phrasing tells you why. It invites information on "purchases of GHG reduction instruments, such as emissions allowances and offsets, from outside the inventory boundary."
Outside the inventory boundary. A provider funding clean energy is doing something outside the boundary of your inventory, which is why it goes in its own line and not against Category 6. Category 6 is defined narrowly: emissions from transporting employees for business in vehicles owned or operated by third parties, aircraft and trains and buses and cars. Solar generation is not in that sentence.
None of this is a judgment about whether the projects are good. It is a question about which column a number goes in, and getting it wrong misstates a disclosure that other people rely on.
The ten-minute test for a vendor's impact report
Three questions, in this order, on any impact report you are handed.
Does it net? Search the document for a travel figure presented after a reduction. Phrases like "net footprint," "your emissions after our impact," or a single headline tonnage with an asterisk. If the travel number and the impact number appear as one, ask for them separated before you go further.
Are the two numbers even the same unit? If the vendor reports generation in megawatt-hours or installed capacity and travel in tonnes of CO2 equivalent, then converting one into the other means assuming a displaced grid mix somewhere else. You should be able to see that assumption. If the conversion is not shown, it is not checkable.
Who signed it, and against what? An impact report with no assurance statement is a marketing document. That is not automatically disqualifying, but it should be priced as one and described that way internally.
ISSA 5000: the assurance standard changes this December
This one is worth catching before your next multi-year contract. The IAASB has withdrawn ISAE 3410, the standard for assurance engagements on greenhouse gas statements, and replaced it with ISSA 5000, the general requirements for sustainability assurance engagements.
ISSA 5000 applies to assurance on sustainability information "reported for periods beginning on or after December 15, 2026, or as at a specific date on or after December 15, 2026." The withdrawal takes effect on the same date.
So a contract you sign this quarter covers reporting periods that fall under the new standard. A vendor whose RFP response promises assurance under ISAE 3410 for a 2027 period is quoting something that will not exist.
That is not a gotcha. Most boilerplate has not caught up yet. But the answer tells you quickly whether anyone on their side is close to the assurance question.
Assurance comes at two levels, limited and reasonable, and limited is the lower one. Ask which level the vendor will sign up to, in the contract, for a named reporting period. The word "assurance" on its own, with no level attached, promises nothing.
What to put in your climate-reporting contract
Four clauses, and none of them require you to have a view on carbon markets.
Separate lines, always. The travel emissions attributable to your bookings, and any funded impact, reported as two figures that are never combined. This is the clause that keeps your disclosure conformant.
The conversion, shown. If the vendor reports impact in tonnes, require the method and the emission factor behind it, in writing, with the source.
An assurance level and a period. Limited or reasonable, under ISSA 5000, for a named period. Plus the right to see the practitioner's report rather than a summary of it.
Your own trips. Segment-level data on your bookings, at an agreed cadence. A vendor that can produce a beautiful annual impact report and cannot give you your own travel is not solving your reporting problem.
What a good climate-impact report looks like
It is duller than the alternative. Two tables that never touch. A travel figure with its methodology named, and a funded-impact figure that names the projects, the instrument, and who retired it.
Then a sentence saying the second is outside the inventory boundary and has not been deducted from the first. A supplier that writes that sentence unprompted has read the standard, which tells you more about them than the size of either number.
Whether your own company may then repeat the claim is a different question, and it turns on who holds and retires the certificate rather than who paid for the hardware. That test is in how employers evaluate transaction-funded climate-impact benefits.
If you are still building the travel number this report is meant to reconcile against, start with verified travel emissions reporting data and the tracking tools comparison.
For the part of the footprint you can remove rather than report, the door-to-door arithmetic is in our rail-versus-air benchmark. How Dyme funds solar sets out our own instrument, which we report as its own line and never against anyone's travel.
FAQ: evaluating a travel provider’s climate-impact report
Can we subtract a provider’s funded climate impact from our travel emissions?＋
No. The GHG Protocol Scope 3 standard requires each category to be reported "independent of any GHG trades, such as purchases, sales, or transfers of offsets or allowances," and requires purchases to be reported separately rather than as a net figure. The funded impact belongs in the optional disclosure the standard describes as instruments "from outside the inventory boundary." Two lines, never combined.
What is the fastest way to check a vendor impact report?＋
Ask three questions. Does it present a net or reduced travel figure? Are the travel number and the impact number in the same unit, and if the vendor converted one, is the method shown? And is there an assurance statement naming a practitioner and a level? All three are answerable from the PDF in about ten minutes, without any view on the underlying projects.
Which assurance standard should a 2027 report be under?＋
ISSA 5000. The IAASB has withdrawn ISAE 3410 and replaced it with ISSA 5000, which applies to sustainability information reported for periods beginning on or after December 15, 2026. A supplier promising ISAE 3410 assurance for a 2027 period is quoting a withdrawn standard. Ask which level they commit to, limited or reasonable, for a named period.
Is an impact report without assurance worthless?＋
Not worthless, but it is a marketing document and should be described that way in your own papers. Plenty of real projects are reported without a practitioner attached. The risk is not that the number is invented. It is that an unassured figure quietly acquires the status of an assured one as it moves through your organization.
Which Scope 3 category covers business travel?＋
Category 6, which the GHG Protocol defines as emissions from transporting employees for business-related activities in vehicles owned or operated by third parties: aircraft, trains, buses and passenger cars. That definition is worth reading next to a vendor claim, because generation funded somewhere else does not fall inside it.
