How Conversion Events Break the 45X MACR Documentation Chain

Two facilities with identical equipment, identical chemistry, and identical nameplate capacity can carry entirely different 45X credit eligibility postures, distinguished by nothing visible from the outside. The divergence sits in the documentation file.

IRS Notice 2026-15, published March 9, 2026, established interim guidance for the material assistance cost ratio (MACR) that taxpayers may rely on for eligible components sold in taxable years beginning after July 4, 2025. One year into that clock, every 45X battery-cell credit claimed carries a documentation burden that did not previously exist: constituent-material tracing, direct-cost accounting, supplier certifications signed under penalty of perjury, six-year record retention. The credit is $35/kWh. The compliance file is what makes it claimable.

Three types of conversion are now occurring simultaneously across the US battery manufacturing base. Chemistry switches. Ownership transfers. Product shifts from EV cells to energy storage. Each breaks different links in the MACR documentation chain, and the breaks range from recoverable to near-total. Mapping them matters because the documentation chain is now a structural component of what a facility's output is worth to its owner.

The MACR File's Components

The MACR is a ratio. Total direct material costs for production of the eligible component, minus direct material costs attributable to prohibited foreign entity (PFE) sources, divided by total direct material costs. The non-PFE share must meet escalating thresholds under Section 7701(a)(52)(C):

Year	Minimum non-PFE share
2026	60%
2027	65%
2028	70%
2029	80%
2030+	85%

To compute this ratio, a taxpayer must identify constituent materials in the eligible component, track their relevant characteristics, determine total direct material costs (including freight-in and tariffs), determine which costs are PFE-sourced, and calculate the MACR. For a battery cell, "constituent materials" covers cathode active material, anode material, electrolyte, separator, current collectors, cell casing, binder, conductive additives. Each carries its own supply-chain provenance. Each requires its own cost allocation.

The operative compliance mechanism is supplier certification. The safe-harbor tables required under Section 7701(a)(52)(D)(iii)(I), which the statute directs Treasury to issue by December 31, 2026, remain unpublished. Notice 2026-15 treats them as a named forthcoming item and provides interim reliance rules until they appear. The Form 7207 page, last updated June 27, 2026, shows no safe-harbor-table publication. Until those tables appear, each supplier certification must:

• Include the supplier's EIN or foreign-government identification number
• Be signed under penalties of perjury
• Be retained by both supplier and taxpayer for at least six years
• Be produced to Treasury on request

The taxpayer may not rely on a certification it knows or has reason to know is inaccurate.

That is the chain, and each conversion type stresses it differently.

Chemistry Switch: Full Reset

When a facility converts from NCA or NMC to LFP, the constituent-material list changes almost completely. Cathode active material shifts from nickel-cobalt-manganese or nickel-cobalt-aluminum oxide to lithium iron phosphate. Precursor supply chain, cathode supplier, cost structure, PFE exposure profile: all change. Electrolyte formulations shift. Cell design changes affect separator and current-collector specifications.

Anode material may remain graphite across chemistries, though sourcing and processing provenance can differ. Graphite's PFE exposure is acute in its own right. The concentration of synthetic and natural graphite processing in PFE jurisdictions means that even when the anode material nominally survives a chemistry switch, the supplier-certification burden for demonstrating non-PFE graphite sourcing is among the heaviest in the constituent-material stack. A chemistry conversion that retains the same graphite supplier simplifies one line item. A conversion that also requalifies graphite supply resets it.

Every supplier certification in the pre-conversion file covers materials no longer incorporated into the eligible component. The MACR denominator changes. The PFE-sourced portion changes. Constituent-material identification, cost allocation, supplier certification: each step restarts.

Section 45X defines a battery cell by electrochemical characteristics: at least one positive and one negative electrode, energy density of at least 100 Wh/L, capacity of at least 12 Wh. Chemistry is not a qualifying condition. An LFP cell meeting these thresholds is as eligible as an NMC cell. The credit remains available after conversion, but the documentation chain supporting it resets completely.

The practical consequence is a gap period. The facility produces cells for which no MACR documentation yet exists. Duration depends on how quickly new supplier certifications can be obtained, new cost allocations performed, new direct-material-cost records established. For a facility qualifying a new cathode supplier that has never produced a perjury-grade certification for a US taxpayer, "quickly" may not be the right word. Each week of that gap represents $35/kWh of production credit that cannot be claimed until the file is rebuilt, assuming it can be rebuilt to the 60 percent threshold at all.

Ownership Transfer: The Taxpayer Changes

Section 45X allows the credit for eligible components "produced by the taxpayer" and "sold by such taxpayer" to an unrelated person. Form 7207 instructions require a separate form for each facility. The credit attaches to the taxpayer, not to the facility.

When ownership transfers, the new owner is a new taxpayer. It files its own Form 7207. It substantiates its own MACR position for components produced and sold post-transfer. The reviewed IRS and Treasury sources do not establish a public rule under which a successor owner automatically inherits a predecessor's MACR file, supplier certifications, or Form 7207 position solely by acquiring a facility.

The predecessor's documentation retains some value. If the new owner continues purchasing from the same suppliers, those suppliers' certifications may remain valid for the new taxpayer's MACR calculation, provided they cover the relevant materials and cost data. But the new taxpayer must independently determine reliance. The six-year retention obligation runs from the new taxpayer's claim date. Section 6418 credit transfers, which allow disposition of a credit already earned to an unrelated buyer for cash, are a distinct mechanism that does not solve the successor-documentation problem.

Ford's May 21, 2026 8-K disclosed that Ford Energy Battery LLC acquired BlueOval SK's interests in two Kentucky battery plants, assuming obligations under a $3.80504 billion DOE note. The taxpayer identity for future 45X claims shifted from a Ford-SK On joint venture entity to a Ford subsidiary. Whatever MACR documentation BlueOval SK had assembled does not automatically transfer to Ford Energy Battery LLC as a matter of public tax law. Ford's entity must build or verify its own file. PFE-mitigation signal disclosed; no public MACR or supplier-certification record.

Product/Application Shift: 45X Survives, Credit Stack Narrows

This is the conversion type where the compliance logic is most favorable to the producer.

Section 45X defines a qualifying battery component by physical characteristics. A cell is a cell. The statute does not condition cell-level eligibility on downstream application. The $35/kWh production credit applies to eligible cells produced and sold to unrelated persons regardless of whether they end up in an electric vehicle or a stationary storage container, provided MACR compliance holds.

The credit stack still narrows. Section 30D, the clean-vehicle credit, expired for vehicles acquired after September 30, 2025. Even before expiration, 30D's battery-component requirements created compliance incentives specific to EV-destined cells. When a facility shifts to ESS production, that vehicle-credit linkage breaks entirely. The 45X production credit can persist if the MACR file remains intact.

And here the conversion types compound. If a product shift occurs without a chemistry change and without an ownership change, the existing MACR documentation chain may survive largely intact. Constituent materials are the same. Suppliers are the same. Cost structure may shift modestly with different cell formats or module configurations, but underlying material provenance does not reset.

If the product shift coincides with a chemistry switch (NMC to LFP for cost optimization in ESS applications, a pattern visible across multiple producers) or an ownership restructuring, the documentation resets stack. Samsung SDI's disclosed plans for StarPlus Energy in Indiana illustrate the chemistry-plus-application compound conversion. Samsung SDI stated in March 2026 that EV lines at StarPlus have been converting to ESS, with LFP mass production expected in Q4 2026, sourcing LFP cathode from Korea's L&F under a KRW 1.6 trillion three-year agreement starting 2027. The constituent-material chain shifts from NMC precursors to LFP cathode, the application shifts from EV to ESS, and the MACR file must be rebuilt around entirely different supplier certifications. Samsung SDI's disclosure names the cathode supplier and timeline but does not disclose facility-level MACR evidence or 45X credit claims. PFE-mitigation signal disclosed; no public MACR or supplier-certification record.

The Ford Kentucky situation illustrates a different compounding risk: the Ford DOE Loan Agreement defines "Product" broadly to include battery and battery energy storage products for both stationary storage and vehicle uses. An ownership change has already occurred. If the facility also shifts chemistry or application mix, that is a compound conversion where multiple MACR chain links break simultaneously. No public filing reviewed here confirms such a compound event at a single facility, but the contractual scope for it exists.

DOE Loan Scope After an Obligor Change

When the obligor on a DOE LPO loan changes, project scope becomes a live question. DOE's BlueOval SK project page, checked July 4, 2026, still lists BlueOval SK LLC as owner and describes the loan as supporting production of batteries "for Ford and Lincoln EVs." The Ford DOE Loan Agreement, filed as an 8-K exhibit, identifies Ford Motor Company as the borrower and defines "Product" to encompass stationary storage alongside vehicle applications. It requires DOE prior written consent for actions that could materially change the nature or scope of the Project.

The mismatch between DOE's public page and the SEC-disclosed restructuring reflects update lag. But it matters for anyone assessing whether DOE-financed capacity is contractually constrained to EV production or has scope for ESS conversion. The loan agreement's broad product definition suggests the latter. DOE's public framing suggests the former. The agreement governs.

DOE LPO loans contain change-of-control provisions requiring prior written consent for specified equity disposals, collateral releases, and obligation transfers. The Ford agreement's existence as a filed exhibit confirms DOE consented to this restructuring. Whether that consent extends to future output-mix conversions is a question the agreement's scope provisions address in principle but enforcement practice has not tested. A conditional commitment, which several other battery facilities hold, carries even less certainty: the project scope may still be negotiable because the loan has not closed.

What Remains Structurally Unknowable

No public facility-level registry of 45X claims exists. Form 7207 filings are not public. No database tracks which facilities have assembled MACR-compliant supplier-certification files, which have attempted and failed, or which have not begun. The safe-harbor tables that would give producers a standardized compliance pathway remain unpublished with less than six months before their statutory deadline.

This opacity is structural. The MACR framework creates a compliance burden that is invisible from outside the taxpayer's own records. A conversion event can change a facility's credit eligibility posture without changing anything observable to the market.

When that chain breaks, capacity does not disappear. Its economic value to the taxpayer changes by $35/kWh until the chain is rebuilt. For facilities undergoing compound conversions, the rebuild timeline is measured in quarters, not weeks.

Compliance documentation has become a capital asset, and conversion events are impairment triggers. SEC-disclosed restructurings in the first half of 2026 suggest those triggers are firing more frequently than the regulatory infrastructure was built to absorb.