BESS Procurement and FEOC: Battery Supply Chains Now Determine Tax Credit Eligibility

In February 2026, the IRS issued Notice 2026-15, providing operational guidance for the Foreign Entity of Concern provisions that now govern battery energy storage tax credit eligibility. The guidance was not a surprise. The legislative direction had been visible since the One Big Beautiful Bill Act introduced FEOC-type restrictions into the Investment Tax Credit framework for energy storage projects. What was underestimated was how directly the compliance obligation maps onto procurement decisions that developers had already made, or were about to make.

For IPPs and renewable developers procuring battery energy storage systems in 2026, the FEOC threshold is not a legal detail to resolve at financial close. It is a supply chain condition that must be satisfied at the point of procurement, and it will need to remain satisfied for the next ten years.

The Constraint Most BESS Supply Chains Cannot Currently Meet

The 2026 FEOC threshold requires that at least 55 percent of a BESS project's manufactured product costs come from non-FEOC sources. The designated foreign entities of concern include China, Russia, Iran, and North Korea. By 2030, the threshold rises to 75 percent. The rule is binary: meet the threshold or lose the entire 30 percent ITC. Non-compliance does not result in a reduced credit. It results in zero credit eligibility and potential 100 percent recapture across a ten-year compliance window.

The structural problem is that the global battery cell supply chain is overwhelmingly concentrated in China. CATL, BYD, CALB, and a small number of other Chinese manufacturers produce the majority of lithium iron phosphate cells used in utility-scale storage projects globally. Electrolyte, separator, cathode, and anode inputs trace primarily to Chinese processing capacity. Even battery systems assembled outside China frequently rely on Chinese cells, which typically represent between 30 and 55 percent of total manufactured cost depending on system configuration and the supplier's cost accounting methodology.

This means that many BESS supply agreements executed in 2024 and early 2025, before the FEOC thresholds were finalized, are now either non-compliant with 2026 requirements or sitting in a compliance grey zone that tax equity investors will not accept. Since January 2025, tariffs on Chinese battery materials and components have also driven manufactured costs up by between 56 and 69 percent for systems sourced through historically dominant supply chains.

What Developers and Procurement Teams Are Getting Wrong

The most common procurement error in this environment is treating BESS compliance as a legal or financial close issue rather than a supply chain issue. Developers often ask counsel whether their supply agreement is FEOC-compliant. The answer is almost always that it depends on documentation, accounting methodology, and supplier disclosures that have not yet been obtained.

Notice 2026-15 made clear that compliance is not self-certifying. Developers must document the manufactured product cost breakdown at the component level, trace the origin of each material input, and demonstrate that non-FEOC content meets the 55 percent threshold using the cost accounting method specified by Treasury. Suppliers who say they are FEOC-compliant are offering a representation. That representation has commercial value only to the extent it is backed by auditable supply chain records that your tax equity investor and lender can independently verify.

A second error is treating FEOC compliance as a procurement milestone rather than an ongoing operational condition. The ten-year recapture window means that any supply chain substitution made after commissioning, including battery replacement under a service agreement, can trigger recapture exposure if the replacement units do not meet the then-current FEOC threshold. Service and warranty contracts need to carry the same compliance requirements as the original procurement.

The third error is underestimating cost impact. The combination of tariff pressure and FEOC compliance requirements is pushing developers toward non-Chinese cell suppliers, primarily Korean, Japanese, and emerging US domestic manufacturers, at a price premium that was not in most project pro formas eighteen months ago. That premium is real, but in most scenarios the 30 percent ITC more than offsets it. The projects that struggle are the ones that modelled ITC eligibility without modelling the supply chain cost of achieving it.

How We Approach BESS Procurement

When we work on battery energy storage procurement for IPP clients and renewable developers, the first question is not which supplier offers the best price per kilowatt-hour. The first question is what the bill of materials looks like, and whether the supplier can produce documentation capable of satisfying the Treasury cost accounting methodology before contract execution.

We source BESS systems where cell origin, electrolyte source, and balance-of-system component traceability can be provided in writing at the time of contract execution, not at financial close. Where compliant options carry a cost premium, we model the net present value of the ITC against the price differential before advising on supplier selection. That calculation is sensitive to project scale, financing structure, and the actual manufactured cost breakdown, which varies materially between suppliers claiming equivalent FEOC compliance.

We also require that service and long-term operations and maintenance agreements carry forward the same FEOC compliance requirements as the initial supply contract. A battery replacement in year six that triggers recapture exposure can destroy a project's financial model. The compliance chain needs to run the full length of the tax equity window, and the contracts that govern operations need to reflect that.

The Supply Chain Decision Is Also the Financial Decision

BESS procurement in 2026 is simultaneously a capital equipment decision, a tax credit eligibility decision, and a decade-long compliance management obligation. The developers navigating it cleanly are the ones who started supply chain qualification before selecting a supplier, rather than attempting to retrofit compliance documentation onto a supply agreement that was structured around a different set of assumptions.

The FEOC threshold will increase. Documentation requirements will become more detailed as Treasury issues further guidance. The supply chain itself will continue shifting as domestic and non-FEOC manufacturing capacity comes online in Korea, Japan, and the United States. Getting the first procurement decision right is significantly easier than correcting it from within a signed supply contract.

Organizations procuring battery energy storage systems in 2026 that want to review supply chain documentation and evaluate FEOC compliance before contract execution are welcome to engage our team at the stage where that review can still affect the outcome.