A high-level summary:
The GHG Protocol Scope 3 Standard is the most widely used framework for measuring and reporting value chain emissions. It was last fully updated in 2011 and is now being revised, with a final version expected in 2027. This March, the GHG Protocol published its Scope 3 Standard Revisions Phase 1 Progress Update — a draft of its proposed changes. While this is not a finalised standard and nothing in it is binding today, it is the clearest signal so far of where carbon accounting is heading, with an increased focus on data completeness, transparency, and comparability.
For business travel, three proposals stand out:
- a 95% coverage requirement that prevents companies from excluding categories without measuring them,
- a requirement to disaggregate emissions by methodology type, making spend-based reporting visible in public disclosures,
- and a structural separation between required and optional emissions, making hotel omissions more visible.
While specific detail relevant to business travel will come in Phase 2, the Phase 1 draft offers the clearest view yet of where reporting is heading. This article outlines the key developments and what they could mean in practice.
The 95% rule: you must quantify a category’s immateriality in order to exclude it from reporting
The update proposes the requirement for companies to report at least 95% of their total Scope 3 emissions, capping cumulative exclusions at 5% supported by quantitative evidence that excluded categories are immaterial.
For business travel, the consequences are meaningful — a company that currently omits Category 6 on materiality grounds can no longer do so without first measuring it, and once measured, the case for continued omission becomes more difficult to justify.
This signals a move towards more complete and auditable carbon inventories and brings business travel emissions back on the radar for many companies.
Mandatory disaggregation: your spend-based data will be a lot more visible.
A more consequential change for day-to-day reporting practice is the proposed requirement to disaggregate emissions data by methodology type. Companies would need to disclose what proportion of their Category 6 figure derives from spend-based estimation, distance-based calculation, or fuel-based data.
Under the proposed changes, that distinction would become visible in public disclosure. The proportion of Category 6 emissions derived from spend-based data will be peer-comparable, meaning organisations with richer data sources — TMC integration, actual itinerary data, carrier and class of travel — will report a methodology mix that looks materially different from those relying on expense data alone.
Where business travel is a significant part of a company's Scope 3 emissions, greater scrutiny may be placed on the granularity of methodologies and data quality.
Want to learn more about the different types of emissions methodologies? Check out our Business Travel Emissions Guide.
Required vs. optional reporting separation: Hotel reporting remains optional, but their omission is now visible
Phase 1 of the draft does not yet confirm whether hotels will move from optional to required within Category 6. However, the draft proposes that optional categories are reported separately rather than folded into the required emissions total, meaning hotel emissions would appear on a distinct line in public disclosure.
The effect of this is more significant than it first appears. Companies reporting Category 6 without hotels will have that omission explicitly visible rather than absorbed into aggregate figures. At the same time, separating optional from required emissions gives companies a cleaner way to expand their reporting scope over time, without compromising the ability to compare mandatory emissions on a consistent basis year-on-year.
Phase two is the one to watch — but preparation starts now
Category-specific boundary changes have not yet been confirmed. Phase 2 of the revision is where the detail on Category 6 will be resolved, including decisions on whether well-to-tank emissions and hotel reporting move from optional to required.
However, Phase 1 clearly sets the tone for the standard revision: tighter coverage thresholds, greater methodological transparency, and a cleaner separation between required and discretionary reporting to enhance comparability.
For travel managers, the message is simple: do not wait for the final standard to act. Understand what proportion of your Category 6 emissions are spend-based, distance-based, or fuel-based, and if your TMC data is incomplete, closing that gap now will put you ahead
