The quick answer

In 2025, the ceiling §45Z value for SAF is essentially $1.75/gal (before inflation) multiplied by your fuel’s emissions factor. If your eSAF (PtL) achieves a near-zero lifecycle emissions rate, your emissions factor ≈ 1.0, so you’re at the top of the §45Z range—provided the project satisfies prevailing wage & apprenticeship (PWA) rules. Treasury’s 2025 guidance confirms the math, and DOE’s new 45ZCF-GREET + CORSIA pathways govern how you compute the lifecycle number. IRS+2IRS+2

Formula you’ll actually use:
Credit per gal = Applicable amount × Emissions factor
Emissions factor = (50 − your emissions rate) ÷ 50 (units: kgCO₂e/MMBtu)
Applicable amount (SAF) = $0.35/gal (base) or $1.75/gal with PWA. IRS+1

Section 45Z eSAF 2025 credit math—$1.75/gal base and (50−CI)/50 emissions factor, with eligibility notes
Credit = $1.75/gal × [(50−CI)/50]; negative CI may lift payout; CORSIA or 45ZCF-GREET and 2025–27 domestic rules apply.

What changed in 2025 (and what counts for eSAF)

  • Two accepted LCA methods for SAF. For 45Z, you can determine a SAF emissions rate via CORSIA (Default or Actual) or DOE’s 45ZCF-GREET model; both are explicitly allowed in IRS Notice 2025-11. That’s vital for Power-to-Liquid pathways that may prefer CORSIA Actual with project-specific data. IRS
  • DOE released 45ZCF-GREET (with user manual). It’s the official model for non-SAF fuels and an option for SAF. DOE updated it in May 2025. The Department of Energy’s Energy.gov+2ethanolproducer.com+2
  • Electricity accounting matters. 45ZCF-GREET lets you apply qualifying energy attribute certificates (EACs/RECs) for solar/wind/hydro to model zero-emissions electricity, which is crucial to keep eSAF’s CI near zero. (Follow the manual’s data entry rules.) The Department of Energy’s Energy.gov

45Z credit math—applied to eSAF (PtL)

  • If CI ≈ 0: Emissions factor ≈ 1.0 ⇒ $1.75/gal in 2025 with PWA (base $0.35 without). Add any IRS inflation adjustment when published for the year of sale. IRS
  • If CI = 5 kgCO₂e/MMBtu: Emissions factor = (50−5)/50 = 0.90 ⇒ $1.75 × 0.90 = $1.575/gal (with PWA). IRS

Eligibility snapshot (for any 45Z fuel, including eSAF):
Produced in the U.S., sold to an unrelated party during 2025–2027 (see extension below), registered producer under §4101, and emissions rate < 50 kgCO₂e/MMBtu. SAF also needs unrelated-party certification under the permitted LCA method. IRS

New law alert: what the OBBBA changed mid-2025

The One Big Beautiful Bill Act (OBBBA) (signed July 4, 2025) extended §45Z through 2029 but modified SAF’s rate after 2025. Headline takeaways:

  • Extension: §45Z runs through Dec 31, 2029. RSM US+1
  • SAF rate after 2025: multiple legal summaries indicate the law removes the extra SAF premium after 2025 (several note a drop to $1.00/gal as the applicable amount). Verify your tax modeling against the enacted text and any IRS updates for 2026+. Sidley Austin+1
  • Feedstock geography & other tweaks: New USMCA-zone feedstock limits and restrictions on negative emissions rates (with narrow exceptions) apply in later years—important for book-and-claim strategies and DAC accounting. RSM US

Bottom line for 2025: 2025 remains the most lucrative year for SAF under §45Z with the $1.75 applicable amount (PWA) before the OBBBA changes bite in 2026+. afdc.energy.gov+1

Where eSAF wins (and how to hit the top of the range)

  1. Go all-in on zero-carbon electricity. For PtL, electricity drives both electrolysis and synthesis. Use qualifying EACs (solar/wind/hydro) per 45ZCF-GREET to model near-zero power. Keep procurement, retirement, and temporal/geographic matching records aligned with evolving IRS/DOE guidance. The Department of Energy’s Energy.gov
  2. Use DAC or other qualifying CO₂ sources under the chosen LCA. CORSIA and 45ZCF-GREET treat feedstock CO₂ differently than sequestration; ensure the pathway and carbon source are modeled correctly to avoid surprises (remember: OBBBA narrows use of negative emissions rates). IRS+1
  3. Lock in PWA from day one. Without prevailing wage & apprenticeship, your applicable amount is only $0.35/gal (2025) vs $1.75/gal with PWA—5× difference before multiplying by the emissions factor. afdc.energy.gov
  4. Pick the optimum LCA path for PtL. CORSIA Actual may reward high-fidelity project data (renewable power, DAC CO₂, efficient plant design). If your exact route isn’t in the table yet, IRS allows a Provisional Emissions Rate (PER) process—watch for the formal petition mechanics before filing. IRS
  5. Mind anti-stacking rules. You can’t stack 45Z at the same facility in the same tax year with 45V (clean H₂) or 45Q. Practically, the hydrogen producer might claim 45V upstream, while the eSAF producer claims 45Z—but not both at one facility for the same production. Structure contracts accordingly. IRS+1

Worked example (2025)

Scenario: U.S. PtL plant produces 5 million gal of eSAF in 2025; PWA satisfied. Verified emissions rate = 3 kgCO₂e/MMBtu (via CORSIA Actual).

  • Emissions factor = (50−3)/50 = 0.94.
  • Credit = $1.75 × 0.94 = $1.645/gal ⇒ $8.23M (§45Z, pre-inflation).
  • If the same plant slips to 2026 with OBBBA’s reduced SAF applicable amount ($1.00/gal, per multiple legal summaries), the same CI would yield $0.94/gal ⇒ $4.7M. (Run your own model with the final IRS inflation factor for each year.) Sidley Austin+1

How to prove your number (and keep it)

  • Methodology choice: For SAF, pick CORSIA Default/Actual or 45ZCF-GREET and apply it consistently across feedstock and fuel stages (per Notice 2025-11). IRS
  • Documentation: Keep complete electricity EACs, DAC CO₂ sourcing, metering, and process energy logs. Follow the 45ZCF-GREET user manual instructions precisely (inputs, rounding, and file versioning). The Department of Energy’s Energy.gov
  • Registration & certifications: Register under §4101, arrange unrelated-party certification for SAF, and ensure sale to an unrelated party. IRS
  • Inflation & updates: §45Z amounts are inflation-adjusted each year; IRS posts factors and may update the emissions rate table—monitor for changes that could shift your EF mid-project. IRS

What about stacking with clean hydrogen (45V)?

Yes, upstream H₂ can claim 45V—just not at the same facility claiming 45Z. Final 45V rules (Jan 2025) clarified CI thresholds and matching for power; developers often model ~1.5 kg H₂/gal eSAF and secure up to $3/kg for that hydrogen at the hydrogen plant while the eSAF plant claims 45Z on the finished fuel—again, separate facilities/taxpayers are key to avoid anti-stacking. The Department of Energy’s Energy.gov+2U.S. Department of the Treasury+2

Diagram showing 45V at a hydrogen plant and 45Z at a separate eSAF plant with 1.5 kg H₂/gal flow
Claim 45V at the H₂ plant (up to ~$3/kg) and 45Z at the eSAF plant—separate facilities/taxpayers, CI and temporal matching apply.

Key pitfalls to avoid

  • Relying on grid-average electricity without EACs—your CI (and credit) will crater. Use the EAC feature in 45ZCF-GREET correctly. The Department of Energy’s Energy.gov
  • Assuming negative emissions “boost.” Post-OBBBA, negative emissions rates are generally prohibited (narrow exceptions apply), so you should model toward ~0, not <0. RSM US
  • Missing PWA—that’s the difference between $0.35 and $1.75 per gal in 2025. afdc.energy.gov
  • Using a method inconsistently. Notice 2025-11 requires that, for a given SAF fuel, you use the same methodology for all stages. IRS

For 2025, PtL eSAF made with renewable electricity (documented via EACs) and DAC CO₂, produced in the U.S. under PWA, can hit the top of §45Z—about $1.75/gal × emissions factor (~1.0)—before OBBBA’s post-2025 rate changes for SAF take effect. From 2026–2029, the credit still matters but the applicable amount for SAF drops, so locking in near-zero CI and clean hydrogen supply (potentially with 45V upstream at a separate facility) becomes the make-or-break for project economics. IRS+1

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