How this tool works
The adder test uses the IRS Elective Safe Harbor (Notice 2025-08): every component of a module, inverter, tracker, or racking system has an IRS-assigned cost percentage. We credit each component's percentage times its U.S. share, add a product's “production” credit only when every component of that product is U.S.-made, and compare the total to your begin-construction threshold (40/45/50/55%). Structural steel and iron are tested separately — 100% U.S. or fail. The FEOC test computes your Material Assistance Cost Ratio — the share of direct manufacturing cost not attributable to a prohibited foreign entity — against the year's threshold (40% for 2026 generation projects, rising yearly).
The document flow: upload whatever paperwork you already have — a purchase order or BOM, the module reliance letter, inverter and racking domestic-content statements, signed FEOC certs — and the analysis reads component-level sourcing, exact SKUs, and equipment counts directly from those documents. Anything a document doesn't establish is treated the way the IRS would treat it: as imported (or, for FEOC, as undetermined). Manual entries you type in the form override the documents, and the report ends with a list of exactly which documents are still missing for a defensible claim — so you know precisely what to request from each manufacturer.
What this tool can't tell you
- Whether the module version that actually ships matches the reliance letter — domestic and global SKUs of the same panel often differ by a suffix. Verify delivered part numbers on the final invoice.
- Whether a supplier is actually a prohibited foreign entity — you may rely on a signed cert unless you have reason to know it's wrong, and an undetermined supplier counts against you.
- Your begin-construction position (physical-work test vs. 5% safe harbor) — that's a facts-and-circumstances call for your tax advisor.
- Anything about your specific tax situation. This is decision-support, not tax advice.
Frequently asked questions
What's the difference between the domestic content adder and FEOC?
They're independent tests that get conflated constantly. The domestic content adder is a carrot: pass and your ITC rises 10 points (30% → 40% on qualifying projects). FEOC is a stick: begin construction after December 31, 2025 with too much prohibited-foreign-entity content and you lose the entire credit — base and adder alike. A project can pass one and fail the other; you have to run both.
Why does fixed-tilt ground-mount almost never pass the adder?
Because fixed-tilt racking, steel piles, and foundations are classified as steel/iron — they must be 100% U.S. (Prong 1) but contribute nothing to the manufactured-products percentage (Prong 2). That leaves only the module and inverter, and the ground-mount inverter column is small. In practice, fixed-tilt needs a domestic-cell (c-Si) module to clear the bar; a tracker changes the math because a tracker is a manufactured product worth up to ~28.7%.
My module is "assembled in the USA." Does that count?
Only partly — and this is the most expensive misunderstanding in the industry. A U.S.-assembled module with imported cells, wafers, and glass typically earns only a few points (frame, junction box, small parts). The cells line alone is worth 31–53 points depending on system type, so where the cells and wafers are made dominates the result. Get a component-level reliance letter, not a country-of-assembly claim.
What paperwork do I actually have to keep?
For the adder: manufacturer reliance letters, final invoices showing the exact (often "-US") part numbers delivered, and the Form 3468 Domestic Content Certification Statement filed with your return — retained at least three years. For FEOC: a signed-under-penalty-of-perjury material-assistance certification from every manufacturer, retained at least six years.
Do the thresholds change if my project slips a year?
Yes, both of them. The adder threshold steps 45% → 50% → 55% across 2025 → 2026 → 2027 begin-construction dates, and the FEOC threshold rises in parallel (40% → 45% → 50% for generation). A bill of materials that passes by half a point in 2026 can fail outright in 2027 — we flag thin margins in the report for exactly this reason.
Is this tool tax advice?
No. It applies the published IRS safe-harbor tables to the sourcing facts you enter, the same way a diligent analyst would on a first pass. Treat the output as the homework you bring to your CPA — it will save you billable hours, but the filing position is between you and your advisor.