What is a Pending Issuance Unit (PIU)?

Quick Answer: A Pending Issuance Unit (PIU) is a placeholder credit issued in voluntary carbon markets to represent a carbon removal or reduction that has been contracted but not yet verified. PIUs carry more risk than fully issued credits because the underlying project outcome is unconfirmed. Once the project delivers and passes verification, PIUs convert into standard verified carbon credits.

What Is a Pending Issuance Unit (PIU)?

A Pending Issuance Unit (PIU) is a forward-looking instrument used in voluntary carbon markets. It represents a tonne of CO2e that a carbon project expects to remove or avoid in the future, issued before that outcome has been independently verified.

PIUs are most commonly associated with nature-based and long-duration removal projects, such as reforestation, soil carbon sequestration, and enhanced weathering. These projects take time to deliver measurable results, so PIUs allow buyers to secure credits in advance, and project developers to access capital earlier in the project lifecycle.

The key distinction is that a PIU is a promise, not a confirmed outcome. It sits at an earlier stage of the credit lifecycle than a verified carbon unit (VCU) or a certified emission reduction (CER), both of which have passed independent third-party verification.

How Do PIUs Work in Practice?

A carbon project developer registers a project with a recognised standard body, such as Verra or Gold Standard, and submits a project design document outlining expected emissions reductions or removals over a defined period. Based on those projections, the registry may issue PIUs corresponding to anticipated future tonnes.

Buyers can then purchase PIUs at a lower price than fully verified credits, reflecting the additional uncertainty. The lifecycle of a PIU typically follows this path:

If a project underdelivers, the number of credits issued on conversion will be lower than the number of PIUs originally sold. In some cases, buffer pools maintained by the registry absorb shortfalls, but buyers should understand that conversion is not guaranteed at the projected volume.

What Are the Risks of Buying PIUs?

PIUs carry a different risk profile to verified credits, and that difference matters for anyone using carbon credits as part of a broader climate strategy.

Delivery risk is the most significant. The project may not remove or reduce as much carbon as projected, due to drought, fire, land-use change, or inaccurate baseline assumptions. Reforestation projects, for example, are vulnerable to wildfires and pest damage over long crediting periods.

Verification risk refers to the possibility that an independent auditor identifies methodological issues or data gaps that reduce the volume of credits issued on conversion.

Timing risk is also relevant. PIUs may be issued years before conversion, meaning a buyer who needs to report verified removals in a specific year cannot rely on PIUs to meet that obligation with certainty.

Liquidity and price risk apply in secondary markets. PIUs trade at a discount to verified credits, and that discount can widen if confidence in a project or standard declines.

For companies using carbon credits as part of a net zero or SBTi-aligned strategy, the distinction between PIUs and verified credits is not a technicality. Reporting a PIU as a retired, verified offset would misrepresent the actual state of the underlying carbon outcome.

Why Does the PIU Distinction Matter for Carbon Reporting?

Carbon accounting frameworks, including the GHG Protocol and guidance from the Science Based Targets initiative, are specific about what constitutes a credible carbon credit claim. Using PIUs in place of verified credits in public-facing claims or compliance submissions creates material integrity risk.

The difference becomes particularly relevant in three situations:

PIUs can play a legitimate role in project financing and long-term procurement planning. What they cannot do is substitute for verified credits in a current-year claim.

How Should Companies Approach PIUs?

PIUs are not inherently problematic. For companies with longer planning horizons, buying PIUs from high-quality projects can be a way to secure future supply of verified credits at a lower cost, while supporting project development at an earlier stage.

A sensible approach involves a few clear principles:

For companies building a carbon reduction strategy, credits of any kind should sit alongside, not in place of, genuine emissions reductions across Scopes 1, 2, and 3. Seedling's approach to carbon management starts with an accurate, full-scope footprint, which gives companies the baseline they need to understand where real reductions are possible before reaching for market-based instruments.

The voluntary carbon market continues to develop its standards around PIU issuance and conversion, with registries including Verra refining their rules in response to scrutiny over credit quality. Staying current with those standards is part of using PIUs responsibly.