David Diaz, Chief Strategy Officer · Technical review: John Kapral, Senior Director, Renewable Energy Tax Incentives & Credits · Updated September 2026
At a Glance
| Question | Short answer |
|---|---|
| Primary credit | Section 48 |
| Potential rate | 30% with applicable requirements; potentially up to 50% with qualifying adders |
| Customer-owned public project | Elective pay may be available under §6417 |
| Taxable owner | Credit may offset liability or potentially transfer under §6418 |
| Main ESCO responsibility | Quantification, compliance coordination and project documentation |
| GHP runway | Construction beginning through 2032 for the 30% tier, subject to applicable requirements |
In a geothermal performance contract, the federal investment tax credit can reach the customer through elective pay, or be monetized through ownership and transfer structures, depending on who owns the system and whether that owner is a tax-exempt or private organization. Either way, 30 to 50 percent of eligible cost can enter the project economics. The ESCO that quantifies it credibly at proposal stage is competing on an axis the low bidder cannot reach.
Public sector RFPs are decided on the business case. When two proposals promise similar savings and one of them shows a defensible path to a federal payment worth 30 percent or more of the eligible geothermal scope, the comparison stops being about price per ton.
Who Claims the Geothermal ITC in an ESCO Performance Contract?
The credit follows ownership, and the owner’s tax status sets how it is captured. Those two facts drive the design of every geothermal deal an ESCO brings to a tax-exempt customer.
Where the district, university or agency owns the system, the customer may claim elective pay under Section 6417 and receive the credit as cash from the IRS. The ESCO does not claim the credit. But the ESCO’s proposal is where the customer first sees the number, and the ESCO’s delivery is what makes the number survivable. Prevailing wage tracking, domestic content documentation and the construction-start file all sit inside the ESCO’s scope of work.
Where a taxable entity owns the system, the credit can offset tax liability or be sold to an unrelated buyer for cash under the Section 6418 transfer rules. That structuring analysis is project-specific and worth running early, because it changes the financing stack rather than just the filing.
Getting this wrong in a proposal is worse than leaving it out. A customer’s counsel who finds a credit assumed for the wrong party discounts the rest of the model, including the savings numbers you did get right.
What Does an ESCO Need to Document for the Geothermal ITC?
The wind and solar begin-construction deadline passed on July 4, 2026, and a good part of the market read that as the end of the ITC. It was not. Geothermal heat pumps (GHP) remain under Section 48, starting at 30 percent for construction beginning through 2032 where prevailing wage and apprenticeship requirements, if applicable, are met. The rate steps down for 2033 and 2034 starts. Domestic content and energy community adders can each add 10 percentage points, which is how a project reaches 50 percent.
Another significant advantage of GHP systems is that the prohibited foreign entity sourcing rules that now shadow Section 48E projects do not apply to Section 48 geothermal heat pump property.
For a pipeline built on public buildings with aging mechanical plants, that is a multi-year runway on exactly the projects already in your funnel, arriving at the moment your competitors stopped mentioning credits at all. In July we reviewed the published content of twelve specialty tax and advisory firms. None of the twelve covered the geothermal credit.
What the proposal needs behind it
Three deliverables separate a credible incentive line from a hopeful one.
A quantified eligibility analysis that states which structure applies, what the eligible basis is likely to include and what rate the project can support, hedged where the facts are still open.
A compliance plan the customer can see: prevailing wage and apprenticeship tracking across subcontractor tiers, domestic content documentation for the elective pay gate on 2026 and later starts, and construction-start evidence. Public sector customers have learned to ask who is doing this work.
A documentation file built during delivery. The customer’s payment arrives after filing, sometimes years after the proposal was signed. What protects it is the record assembled while the rigs were on site, not the one reconstructed afterward.
Walker Blue supports ESCOs nationally with proposal-stage credit quantification on RFP timelines, then the certification and compliance file through closeout. Your proposal carries the number. Our file stands behind it.
Questions ESCOs ask about the geothermal ITC
Can an ESCO claim the geothermal ITC?
Only when the ESCO owns the geothermal heat pump property at the time it is placed in service. On a customer-owned system the credit belongs to the customer, and a school district, university, municipality or other applicable entity may elect to receive it as a direct payment under Section 6417. Under an ESCO-owned or third-party-owned structure, the credit sits with the taxable owner, who may apply it against tax liability or sell it to an unrelated buyer under Section 6418. Ownership is a contract structure decision, so make it before the proposal is priced.
What credit rate does a geothermal heat pump project qualify for?
Section 48 sets a 6 percent base rate for geothermal heat pump property, rising to 30 percent where prevailing wage and apprenticeship requirements are met. Systems under the statutory one megawatt threshold, measured in electrical or thermal output, may qualify for the 30 percent rate without them. The domestic content bonus and the energy community bonus each add 10 percentage points at the 30 percent tier, so a qualifying project may reach 50 percent. The 30 percent tier covers construction beginning through 2032; it steps down to 26 percent for construction beginning in 2033 and 22 percent for 2034, and property beginning construction after 2034 does not qualify. The low-income communities bonus under Section 48(e) is limited to solar and wind facilities under five megawatts and does not extend to geothermal heat pumps.
Do the prohibited foreign entity rules apply to geothermal heat pumps?
No, not to Section 48 geothermal heat pump property under current guidance. The material assistance cost ratio and the related prohibited foreign entity restrictions enacted in July 2025 attach to Section 48E and Section 45Y facilities beginning construction after December 31, 2025, with interim guidance in Notice 2026-15. Geothermal electricity generation, including enhanced geothermal systems, is Section 48E property and does carry those rules. A heat pump scope therefore avoids the sourcing ratio failure that can eliminate an entire Section 48E credit. Treasury’s proposed regulations remain pending, so re-check before pricing a project that mixes technologies.
Does the domestic content requirement affect a customer using elective pay?
Yes, and it is separate from the domestic content bonus. Under Section 6417, an applicable entity that elects direct pay on a project beginning construction in 2026 or later and does not meet the domestic content requirement receives no payment for that credit, unless an exception applies. The exceptions include projects under one megawatt and the cost and availability exceptions in Treasury guidance. On a customer-owned geothermal system this makes domestic content documentation a gate, and it belongs in the procurement plan before the heat pumps and loop materials are ordered.
When does the customer receive the elective payment, and how should the proposal show it?
After the customer completes pre-filing registration with the IRS and files the return for the tax year in which the system is placed in service. A system placed in service in 2027 is claimed on a return filed in 2028, and the payment follows IRS processing. The proposal should show the credit as a lagged cash inflow on the sources and uses side. It is a one-time payment and does not belong in the guaranteed annual savings line. Whether it can count toward the contract guarantee at all depends on the state performance contracting statute and the customer’s counsel; the safer default is a capital cost offset with its own timing line.
What documentation should the ESCO build during delivery?
Four files. Beginning-of-construction evidence, which for Section 48 geothermal heat pump property follows the physical work test or the 5 percent safe harbor, with the continuity requirement. Prevailing wage and apprenticeship records across every contractor and subcontractor tier, including certified payroll, apprenticeship hours, and any correction payments. Domestic content cost documentation for steel, iron, and manufactured products, with supplier certifications. Placed-in-service and cost records that support the eligible basis. All four start at notice to proceed.
Geothermal scope in your pipeline? Walker Blue supports ESCOs nationally with proposal-stage ITC quantification, elective pay support for customers, and audit-ready compliance documentation. Talk to us before the next RFP.
Published August 2026. Updated September 2026 after technical review by John Kapral, Senior Director, Renewable Energy Tax Incentives & Credits. Regulatory figures reflect law and guidance as of September 2026 and are re-verified on each engagement. General educational information, not tax advice.
