Clean Fuels — United States

The US Renewable Fuel Standard (RFS)

Federal Biofuel Mandate — Compliance Guide & Credit Intelligence

The largest biofuel mandate in the world, and the programme that prices the barrel Canadian, European and Asian buyers compete for. It is also routinely misread, because almost every number published about it is denominated in a unit that is not a gallon.

Market Snapshot ● Active & Trading
Market TypeVolumetric Biofuel Mandate
AdministratorUS Environmental Protection Agency
Legal BasisClean Air Act §211(o); 40 CFR Part 80
Compliance UnitRIN — one ethanol-equivalent gallon
Obligated PartiesRefiners & importers of gasoline and diesel
Compliance PeriodCalendar year

Volumes shown are EPA final applicable volumes for 2026, in billions of RINs, including partial reallocation of exempted small-refinery volumes.

RIN
Compliance Unit
26.81bn
2026 Total Volume
4
Nested Obligations
D3–D7
Credit Codes
2005
Programme Since
Market Mechanics

How the US RFS Works

EPA sets an annual percentage standard on refiners and importers of gasoline and diesel. Each party multiplies that percentage by its own fuel volumes to arrive at a Renewable Volume Obligation, then discharges it by retiring Renewable Identification Numbers. The unit is not a gallon, and that single fact accounts for most of the confusion around the programme.

2005
Programme Established
The Energy Policy Act creates the Renewable Fuel Standard under Clean Air Act §211(o), setting the first federal volumetric biofuel requirements.
2007
Expanded to RFS2
The Energy Independence and Security Act expands the programme substantially, adds the advanced, biomass-based diesel and cellulosic categories, and introduces lifecycle GHG thresholds.
2010
RINs Move to EMTS
Renewable Identification Numbers become data elements in EPA's Moderated Transaction System rather than 38-digit strings attached to batches.
2022
Statutory Volumes Expire
The volumes written into statute run out. From this point EPA sets applicable volumes through rulemaking, which is why each multi-year rule matters more than it used to.
April 2026
2026–2027 Volumes Finalised
EPA finalises applicable volumes for 2026 and 2027, including a partial reallocation of exempted small-refinery volumes into the standards.
Programme Structure

Four Obligations, Nested Inside One Another

The standard is not one target but four, arranged as concentric circles. Each fuel earns a RIN with a D-code, and a RIN from an inner circle satisfies every circle outside it. That asymmetry is the economics of the whole programme.

D3 / D7
Cellulosic Biofuel
The innermost circle
Fuels from cellulosic feedstocks, carrying the highest lifecycle GHG reduction threshold. Chronically undersupplied against target, which is why EPA has repeatedly used its waiver authority here.
  • Cellulosic ethanol
  • Renewable natural gas from landfill and digester gas
  • Cellulosic diesel (D7)
D4 / D5
Biomass-Based Diesel & Advanced
Where the market clears
Biomass-based diesel (D4) and other advanced fuels (D5). A D4 RIN satisfies the diesel target, the advanced target and the total at once, which is why it carries optionality that a conventional RIN does not.
  • Biodiesel (FAME)
  • Renewable diesel
  • Renewable jet fuel
  • Other advanced biofuels
D6
Conventional Renewable Fuel
The outermost circle only
Predominantly corn ethanol. A D6 RIN reaches only the total renewable fuel obligation, satisfying none of the inner circles. Abundant, and priced accordingly.
  • Corn ethanol
  • Other conventional biofuels meeting the 20% threshold
Design Features

Key Design Features

Six features of the regulation that determine how the market actually behaves — and which are the ones most often missed when a project is sized against the programme.

Counted in RINs, Not Gallons

One RIN is one ethanol-equivalent gallon. A physical gallon generates RINs in proportion to its energy content under equivalence values fixed in the regulation — ethanol 1.0, biodiesel 1.5, renewable diesel 1.7, butanol 1.3. Renewable natural gas is credited at 77,000 Btu per RIN.

Obligations Nest Downward

A RIN from an inner circle satisfies every circle outside it. This is what gives D4 and D3 their optionality, and why the spread between D4 and D6 is the single most watched relationship in the market.

The Diesel Target Is Not the Constraint

Because the obligations nest, biomass-based diesel covers its own line and also fills whatever the advanced circle cannot get elsewhere. The real pull sits above the stated diesel target — the gap is spillover, not the diesel line.

Exports Retire RINs

An exporter incurs an obligation equal to exported volume multiplied by the equivalence value, and must retire RINs within 30 days. A RIN cannot satisfy a US obligation once the fuel has left the country.

Limited Carry-Forward

A RIN is valid in the year it is generated and the following year. Prior-year RINs may cover no more than 20% of an obligation, and a compliance deficit may be carried one year but not two consecutively.

Small Refinery Exemptions

Refineries below a size threshold may petition for exemption on hardship grounds. Exempted volumes, and whether EPA reallocates them into the standards, materially change the effective obligation on everyone else.

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Advisory & Platform

How Climate Decode Supports US RFS

Where the programme meets a specific barrel, a specific plant or a specific contract — that is the work. Six ways we support participants in the RFS.

1. Pathway Registration & Recordkeeping

EPA registration, pathway determination and the recordkeeping that survives an attest engagement. Getting the D-code right at registration is far cheaper than correcting it later.

2. Obligation & RIN Position Modelling

Translating a percentage standard into your actual RVO, and modelling the RIN position that discharges it across D-codes, vintages and the 20% carry-forward limit.

3. Equivalence & Volume Reconciliation

Converting between physical volumes and RINs correctly across fuel types — the step where project models most often go wrong by a wide margin.

4. Cross-Programme Positioning

How a barrel positioned for the RFS interacts with Canada's CFR, California's LCFS and the other clean fuel programmes. Which combination pays best is specific to the barrel.

5. Market & Policy Monitoring

Rulemakings, waiver decisions, exemption petitions and litigation — tracked for what they do to your obligation, not as general news.

6. Compliance Assurance

Annual compliance reports, attest engagement preparation and export RIN retirement, so the obligations land on time and in the right accounts.

Research

US RFS Insights & Analysis

Published analysis from the Climate Decode team on the RFS and the clean fuel markets it sits alongside.

Sources & References

US EPA — Renewable Fuel Standard Program ↗ EPA — Final Renewable Fuel Standards for 2026 and 2027 ↗ 40 CFR Part 80 Subpart M — RFS regulations ↗ 40 CFR 80.1415 — Equivalence values ↗ EPA — RIN trades and price information ↗ EPA — Small refinery exemptions under the RFS ↗

Figures on this page are taken from EPA's published rules and data. EPA publishes RIN generation and transaction data rather than a settled price series, so any RIN price should carry the date and source it came from — the market can move materially in a single session.

FAQ

US RFS — Common Questions

Is an RFS volume the same as gallons of fuel?

No. RFS obligations are denominated in RINs, where one RIN is one ethanol-equivalent gallon. A physical gallon generates RINs in proportion to its energy content — renewable diesel at 1.7, biodiesel at 1.5, ethanol at 1.0. An obligation quoted as 9.07 billion therefore corresponds to well under 9.07 billion gallons of fuel, and comparing an RFS volume directly against a production statistic will mislead every time.

What is a D-code, and why does it matter?

Every RIN carries a D-code identifying the fuel category that generated it — D3 cellulosic, D4 biomass-based diesel, D5 advanced, D6 conventional, D7 cellulosic diesel. Because the obligations nest, a D4 RIN satisfies the diesel, advanced and total targets at once while a D6 reaches only the total. That is the source of the price spread between them.

Who has to comply with the RFS?

Refiners and importers of gasoline and diesel. EPA sets an annual percentage standard; each obligated party applies it to its own fuel volumes to calculate its Renewable Volume Obligation, then retires RINs to discharge it. The compliance period is the calendar year.

What happens to RINs when fuel is exported?

Exporters incur an obligation equal to the exported volume multiplied by the applicable equivalence value, and must retire RINs to cover it within 30 days of export. A RIN generated in the United States cannot satisfy a US obligation once the fuel has left the country.

Can RINs be banked between years?

Within limits. A RIN is valid in the year it is generated and the following year, and prior-year RINs may cover no more than 20% of an obligation. A compliance deficit may be carried forward one year, but not two consecutively.

How does the RFS interact with Canada's CFR or California's LCFS?

They are separate programmes with separate units, and a credit created in one does not transfer to another. A single physical barrel can, however, be positioned against more than one programme depending on where it is produced and where it is consumed. Which combination pays best is specific to the barrel, the feedstock and the pathway — that is the kind of question our advisory work answers.

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