# What is additionality, and how is it actually tested for a carbon project?

Canonical: https://senseible.earth/answers/what-is-additionality-in-carbon-credits

A project is additional if its emission cuts would not have happened without carbon credit revenue. It is tested by showing the project is not required by law, is not the cheapest option without credits, faces real barriers, and is not already common practice, or by qualifying for an approved positive list.

## Why additionality matters

A carbon credit claims that one tonne of CO2e was avoided or removed because of the project. If the project would have gone ahead anyway, the buyer's offset claim is not backed by any real change. The ICVCM Core Carbon Principles list additionality as one of the tests a credit must pass to carry the CCP label.

## The standard tests, step by step

This sequence comes from the CDM Tool for the demonstration and assessment of additionality (Tool 01), which Verra and other programmes still reference.

1. Regulatory surplus: the activity is not required by any law or regulation that is enforced.
2. Identify alternatives: list realistic options, including carrying on as today.
3. Investment analysis: show that without credit revenue the project's return falls below a benchmark, such as a sector hurdle rate, or that it is not the least-cost option.
4. Barrier analysis: as an alternative to the investment test, show barriers such as lack of finance, technology or skills that credit revenue helps overcome.
5. Common practice analysis: show the technology is not already widely used by similar plants in the same region. If it is, the project is presumed non-additional.

## Simplified routes for small projects

CDM Tool 21 sets out simpler additionality for small-scale projects, and some technologies are on positive lists that treat them as additional automatically, usually very small or clearly uneconomic activities. Each methodology states which route applies, so the methodology chosen decides how much proof you need.

## Red flags a buyer should check

- The project earned good returns from power or product sales alone, such as large grid-connected solar or wind in a market where they are already the cheapest new power.
- The project was built and running years before it considered carbon credits, with no record of credits being part of the decision.
- The validation report does not show the benchmark used or the sensitivity analysis.
- The activity is now required by a regulation that came in after registration.

## Illustrative investment test

- Benchmark return for the sector: 12% a year (illustrative)
- Project return without credit revenue: 9%, below the benchmark
- Project return with expected credit revenue: 13%, above the benchmark
- Result: credit revenue changes the decision, which supports additionality, if the inputs survive a sensitivity check of about 10% either way

Figures are illustrative. A real test uses the benchmark and input values set in the methodology and checked by the validation body.

## What Senseible does here

Senseible does not test additionality or validate projects. Credit issuance belongs to registries such as Verra and Gold Standard, not to Senseible; its carbon credit eligibility signals only point out where a project might qualify.

- [ICVCM Core Carbon Principles](https://senseible.earth/answers/what-are-icvcm-core-carbon-principles)
- [Why ICVCM rejected renewable energy credits](https://senseible.earth/answers/why-icvcm-rejected-renewable-energy-credits)
- [Carbon credits from solar installations](https://senseible.earth/climate-intelligence/carbon-credits-solar-installations-monetize)

Sources: [CDM Methodological Tool 01, demonstration and assessment of additionality; Tool 21, small-scale additionality (UNFCCC)](https://unfccc.int), [ICVCM Core Carbon Principles and Assessment Framework](https://icvcm.org), [Verra VCS Standard](https://verra.org)

Last reviewed 2026-10-15.