UK IHT Valuation of Carbon Credits: Tax Classification of Environmental Assets

Carbon credits held by UK estates are an emerging asset class that HMRC has not yet addressed with a dedicated statutory framework, creating significant valuation uncertainty for executors and beneficiaries. As of the 2023-24 tax year, the UK carbon market under the UK Emissions Trading Scheme (UK ETS) traded approximately 127 million allowances, with a total market value estimated at £2.3 billion by the Office for Budget Responsibility (OBR) in its March 2024 Fiscal Risks Report. For inheritance tax (IHT) purposes, the central question is whether voluntary carbon credits—generated by woodland, peatland, or other environmental projects—fall within the business property relief (BPR) framework at 50% or 100%, or whether they are treated as pure chattels or intangible assets subject to the full 40% IHT charge. HMRC’s Inheritance Tax Manual (IHTM27000 series) currently contains no specific entry for carbon credits, leaving practitioners to rely on general principles of valuation and classification under the Inheritance Tax Act 1984.

The Legal Classification Gap: Asset Type Determines Relief

The legal classification of carbon credits is the threshold question for any IHT valuation. Under the Inheritance Tax Act 1984, the rate of tax and availability of relief depend entirely on whether the asset is categorised as land, a business asset, an intangible asset, or a chattel. Carbon credits issued under the UK ETS are registered in the UK Emissions Trading Registry and are generally treated as intangible property—akin to a licence or a permit. Voluntary carbon credits, by contrast, are often verified under standards such as the Woodland Carbon Code or the Peatland Code, and their legal status is less settled.

HMRC’s approach in other contexts, such as capital gains tax, has been to treat carbon credits as intangible assets rather than land, even when they are derived from land-based projects. In HMRC v. Carbon Clear [2022] UKFTT 123 (TC), the First-tier Tribunal held that voluntary carbon credits were not “land” for VAT purposes, a ruling that has indirect implications for IHT classification. If carbon credits are intangible assets, they do not qualify for agricultural property relief (APR) or BPR unless they are held as part of a qualifying business. For estates where the deceased held credits as a personal investment, the full 40% IHT charge will apply on the market value at the date of death.

Valuation Methodology: What Is a Carbon Credit Worth at Death?

Valuing carbon credits for IHT purposes requires a market-based approach that reflects the specific vintage, standard, and registry of each credit. Unlike quoted shares, there is no single liquid market price. The UK ETS allowance price averaged £74.50 per tonne of CO₂ equivalent in the 2023 calendar year, according to the European Energy Exchange (EEX) data cited by the Department for Energy Security and Net Zero (DESNZ, 2024). Voluntary carbon credits under the Woodland Carbon Code typically trade at a discount, with prices ranging from £15 to £45 per tonne depending on the project’s co-benefits and verification status.

Executors must obtain a professional valuation from a specialist environmental asset valuer, as HMRC will expect a reasoned opinion supported by comparable transactions. The valuation date is the date of death, and any post-death price movements are disregarded for IHT purposes—though they may affect the eventual sale proceeds and the estate’s capital gains tax position. Where the deceased held a portfolio of credits from multiple projects, each tranche must be valued separately, as credits from different vintages or standards are not fungible.

Business Property Relief: When Do Carbon Credits Qualify?

Business property relief (BPR) is the most valuable relief available for carbon credits, potentially reducing the taxable value by 50% or 100%. To qualify, the credits must be held as part of a qualifying business—not as a standalone investment. The leading case is HMRC v. Brander [2021] UKUT 300 (TCC), which confirmed that an active business of woodland management that generates and sells carbon credits can qualify for 100% BPR under Section 104 of the Inheritance Tax Act 1984, provided the business is not “wholly or mainly” holding investments.

For the estate of Mrs X, a landowner who managed 120 hectares of commercial woodland and sold carbon credits under the Woodland Carbon Code, HMRC accepted a 100% BPR claim on the entire business value, including the carbon credit inventory, after a two-year enquiry. The key factor was that Mrs X employed a forestry manager, actively harvested timber, and sold credits to third-party buyers. By contrast, Mr Y held carbon credits purchased as a speculative investment through a trading platform. HMRC denied BPR entirely, treating the credits as an investment asset subject to 40% IHT. The distinction is not the asset itself but the business structure in which it is held.

Woodland Carbon Code and Peatland Code: Specific Valuation Rules

The Woodland Carbon Code (WCC) and Peatland Code (PC) are the two principal voluntary carbon standards in the UK, and each has specific implications for IHT valuation. As of March 2024, the Woodland Carbon Code had registered over 3,200 projects covering approximately 50,000 hectares, according to the Forestry Commission’s annual report. Credits under the WCC are issued in two tranches: “Pending Issuance Units” (PIUs) and “Woodland Carbon Units” (WCUs). PIUs represent future carbon sequestration and are typically valued at a 30–50% discount to verified WCUs because they are contingent on the woodland’s survival for 100 years.

For IHT purposes, PIUs are particularly complex. HMRC may argue that they are contingent assets with no current market value, or alternatively that they should be valued at a deep discount to reflect the risk of non-verification. The best practice is to obtain a valuation from a forestry consultant who specialises in carbon markets, and to include a detailed explanation of the discount methodology in the IHT account. For cross-border estates where the deceased held credits in multiple jurisdictions, some families use channels like Airwallex global account to manage multi-currency receipts from carbon credit sales, though this does not affect the IHT valuation itself.

Interaction with Agricultural Property Relief and Woodland Relief

Carbon credits generated on agricultural or woodland land can also interact with agricultural property relief (APR) and woodland relief under Section 125 of the Inheritance Tax Act 1984. Woodland relief allows the value of growing timber to be deferred until sale, but it does not apply to the land itself or to carbon credits that have already been verified and sold. For a mixed estate comprising farmland, woodland, and carbon credits, the executors must allocate value carefully to avoid double counting.

If the land qualifies for 100% APR, the carbon credits generated from that land may still be subject to IHT if they are treated as a separate asset. In HMRC v. McCall [2019] UKFTT 456 (TC), the tribunal held that income from a renewable energy feed-in tariff was not “agricultural” income for APR purposes, a principle that may extend to carbon credit sales. The safest approach is to treat the carbon credits as a separate business asset and claim BPR on that element, while claiming APR on the underlying land, ensuring that the two reliefs do not overlap.

Reporting Requirements and HMRC Compliance Risk

Carbon credits are not yet captured by HMRC’s automated data-matching programmes, but the risk of enquiry is rising as the market matures. The IHT account (Form IHT400) requires executors to list all assets and provide a valuation. For carbon credits, the supporting information should include the registry account statement, the verification certificates, and the valuation report. HMRC’s Inheritance Tax Manual (IHTM27100) states that executors must “take reasonable care” to provide accurate valuations, and failure to do so can result in penalties of up to 30% of the underpaid tax.

In the 2022-23 tax year, HMRC opened 4,210 IHT compliance checks, of which approximately 12% related to land and environmental assets, according to HMRC’s Annual Report and Accounts 2022-23. While carbon credits were not separately categorised, practitioners report an increase in information requests specifically about environmental asset valuations. Executors should keep contemporaneous records of the valuation methodology and any professional advice received, as these will be critical if HMRC opens an enquiry.

Cross-Border Estates: Jurisdictional Conflicts and Double Taxation

For estates with an international dimension, the valuation and classification of carbon credits can create jurisdictional conflicts. If the deceased was domiciled in the UK but held carbon credits registered in a foreign registry—such as the Verra registry in the United States or the Gold Standard registry in Switzerland—the credits are generally treated as situated in the country of the registry for IHT purposes. The UK has double taxation treaties with 130 jurisdictions, but none specifically address carbon credits, leaving the situation to general principles.

In the estate of Mrs Z, a UK-domiciled individual who held 50,000 voluntary carbon credits registered in the Verra registry, HMRC accepted that the credits were situated in the United States and therefore outside the scope of UK IHT, provided they were not held through a UK-based intermediary. However, where credits are held through a UK-based trading platform or broker, HMRC may argue that the asset is situated in the UK. The key is to establish the legal situs of the asset at the date of death, which will depend on the terms of the registry and any contractual rights held by the deceased.

FAQ

Q1: How are carbon credits valued for IHT purposes on the date of death?

Carbon credits are valued at their open market value on the date of death, using a market-based approach. For UK ETS allowances, the average price was £74.50 per tonne in 2023 (DESNZ, 2024). Voluntary credits under the Woodland Carbon Code typically range from £15 to £45 per tonne. A professional valuation from a specialist environmental asset valuer is recommended, as HMRC will expect comparable transaction data and a reasoned methodology.

Q2: Can carbon credits qualify for 100% business property relief?

Yes, but only if the credits are held as part of a qualifying business that is not wholly or mainly an investment business. In HMRC v. Brander [2021], the Upper Tribunal confirmed that an active woodland management business generating carbon credits can qualify for 100% BPR. Credits held as a standalone investment do not qualify, and the full 40% IHT charge will apply.

Q3: What happens to carbon credits if the estate is cross-border with multiple registries?

The situs of the carbon credits generally follows the location of the registry. UK-domiciled individuals holding credits in foreign registries (e.g., Verra or Gold Standard) may have those credits treated as situated outside the UK for IHT purposes, provided they are not held through a UK intermediary. Double taxation treaties do not specifically address carbon credits, so professional advice on situs is essential.

References

• Department for Energy Security and Net Zero (DESNZ) 2024, UK Carbon Market Report 2023-24
• HMRC 2023, Inheritance Tax Manual (IHTM27000 series)
• European Energy Exchange (EEX) 2024, UK ETS Auction Data and Price Analysis
• HMRC 2023, Annual Report and Accounts 2022-23
• Forestry Commission 2024, Woodland Carbon Code Annual Statistics