Federal R&D tax credit substantiation. The trace the IRS reads three years after the return.
If you're searching this after an IRS letter or before extension day — Form 6765 supporting memo for a year I claimed without one, §41(d)(4) exclusion check on activities the CPA waved through, R&D credit I didn't take in 2024 — the page is for you.
IRC §41 credit support — Form 6765, per-activity defensibility memos, §41(d)(4) typed exclusion gate, CPA hand-off bundle.
The credit dollar that cannot trace becomes the IRS audit dollar plus 20% penalty plus interest.
RDTAX prepares the substantiation record for a federal R&D tax credit under §41. The deliverable is not a filed return. The deliverable is what the IRS reads three years after the return — the Form 6765 supporting memo, the per-activity defensibility memos, the contemporaneous-evidence index, the CPA hand-off bundle.
The credit dollar that cannot trace becomes the IRS audit dollar plus 20% accuracy-related penalty plus interest. Most R&D tax credit software vendors produce the dollar without the trace and ship it to the CPA. RDTAX produces the trace and lets the dollar follow from it.
Every §41(d) prong assertion — permitted purpose, technological in nature, elimination of uncertainty, process of experimentation — points at evidence dated within the tax year of the claim. Every §41(d)(4) statutory exclusion is tested per activity, not asserted as a blanket. The check itself is part of the defense; an auditor reading the memo three years later looks for the check, not the conclusion.
Qualified Research Expenses, Regular method, ASC method, QSB applicability. Pure arithmetic. No LLM. The number you walk to the CPA with.
Decompose activities. Score each against the four §41(d) prongs — permitted purpose, technological, uncertainty, experimentation. Run the §41(d)(4) statutory-exclusion check per activity. Output: activities that qualify, activities that don't, named reasons.
Decompose + score + aggregate + compute + audit-readiness write-up + per-activity fix paths. The brief that travels to the CPA and to the eventual auditor — three years later.
Voice-locked, citation-traced, §41(d)(4) gate-passed. The memo your CPA attaches. The memo an IRS examiner reads after the return.
One memo per qualified activity. Cites evidence dated within tax year. Audit-readable on its own.
Structured JSON for tax software — QREs by category, activities by §41(d) status, citations indexed by evidence_id. Drops cleanly into Drake, Lacerte, ProSystem, CCH.