Multi-Entity Filers

R&D Tax Credit Controlled Group Due Diligence

If related entities share common ownership, the R&D credit must be computed for the whole group and allocated among members. Here's the documentation and Form 6765 detail multi-entity owners need under IRC §41(f) for 2024–2026.

Last reviewed: June 2026Reviewed by: MainStreet's R&D Tax Credit team (licensed CPAs & Enrolled Agents)

Quick answer

What does controlled group due diligence require for the R&D credit?

Under IRC §41(f), a group of entities under common ownership is treated as a single taxpayer for the research credit. That means you must aggregate qualified research expenses (QREs) and historical gross receipts across every member, compute one group credit, and allocate it to each entity in proportion to its share of QREs.

Doing this defensibly requires four documentation layers: group structure (org charts, cap tables, §318 attribution, and a credit allocation attachment), qualified research (business component descriptions and four-part-test mapping), QRE substantiation (W-2 wages with a three-way time split, supply invoices, and third-party contracts), and base-period history (group-wide gross receipts and QREs back to 1984–1988). All records must be contemporaneous — reconstructed records will not survive an IRS exam.

Group Structure Documentation §41(f)(5) · §1563

Org charts & cap tables — the ownership chain for every group entity, with the ownership percentage per common owner, dated December 31.
Entity agreements — operating agreements, bylaws, and partnership documents for each entity.
§318 attribution analysis — trust agreements and attribution documentation wherever constructive ownership rules apply.
Group credit attachment — on each member's return: aggregate QREs, the member's proportionate share, the allocated credit, and the §280C statement.

Qualified Research Activities §41(d) · Four-Part Test

Business component descriptions — by type: product, process, software, formula, technique, or invention.
Technical uncertainty docs — what was not known at project outset; genuine uncertainty that existed before work began.
Experimentation records — hypotheses tested, alternatives evaluated, and results, including failures.
Four-part test mapping — permitted purpose, technological nature, elimination of uncertainty, and process of experimentation.

New to the four-part test? See does your work qualify — industries & activities and the business components documentation guide.

Wage QREs §41(b) · §3401(a) · W-2 Only

Payroll journals & W-2s — federal taxable wages only; exclude 401(k), benefits, and pretax deductions.
Time tracking by component — the direct research / direct supervision / direct support split, per project.
Job descriptions — written justification per role, especially critical for officers.
Officer wage support — courts have excluded officer wages without documented time allocation (Moore v. Commissioner).

Supply & Contract QREs §41(b)(2) · §41(d)(4)(H)

Supply invoices & POs — a direct link to a qualified research activity is required; general supplies are excluded.
G/L records by project — expense entries coded to specific qualified research components.
Third-party research contracts — full copies covering compensation structure, IP / rights terms, and payment terms.
Funded research screen — third-party funded expenses are not QREs; review every contract.

Base Amount & History §41(c) · Fixed-Base %

Historical gross receipts — all group members aggregated back to the base period (1984–1988).
Historical QREs — all open years — the group-wide aggregate for all open tax years, not single-entity.
Acquisition / disposition docs — trade-or-business changes since 1984 affecting the fixed-base percentage calculation.
Fixed-base % workpapers — full group history is required; a single-entity computation is a common exam error.

Form 6765 Requirements Phase-In: 2024 → 2026

Items A & B

§280C election plus mandatory controlled group membership disclosure (required starting 2024).

Sections E & F (2024+)

Component count, officer wages, and a QRE summary with the 3-way wage split (direct research, direct supervision, direct support).

Section G (2026 mandatory)

Per business component: name, type, information sought, wages by activity, and supply & contract research costs.

80% / Top 50 Rule

Report the top 80% of QREs, capped at a maximum of 50 components — applied per entity for separate controlled group filers.

For the broader filing mechanics, see the methodology & Form 6765 filing guide.

Practical Due Diligence Summary for a Controlled Group

Documentation Layer	Who Owns It
Ownership / org charts, cap tables, entity agreements	Group-level / tax counsel
Controlled group credit allocation attachment	Filed with each member's return
Business component project descriptions	Each entity with QREs
Employee time records (3-way split)	Each entity with wage QREs
Officer wage substantiation	Each entity
Supply invoices tied to projects	Each entity
Third-party research contracts	Each entity
Historical gross receipts & QREs (base period)	Group-level aggregate
Form 6765 Sections E, F, (G)	Each entity filing separately

Key rule: All records must be contemporaneous — retroactive reconstruction will not satisfy IRS examination standards. See the audit & IDR readiness guide for what the IRS requests in an exam.

Frequently Asked Questions

Under IRC §41(f), a controlled group is a set of related entities (parent-subsidiary, brother-sister, or combined groups) treated as a single taxpayer for the research credit. Common ownership is tested using the §1563 rules, with §318 attribution applied where applicable. Once entities are part of a controlled group, the credit must be computed on a group-wide basis and then allocated among members.

Because the group is treated as one taxpayer, you must aggregate qualified research expenses (QREs) and historical gross receipts across all members to compute the group credit, then allocate it to each entity in proportion to its share of QREs. Computing the credit — and especially the fixed-base percentage — on a single-entity basis is one of the most common examination errors for multi-entity owners.

The group computes one aggregate credit, then allocates it to each member in proportion to that member's share of the group's QREs. Each member attaches a group credit statement to its return showing aggregate QREs, its proportionate share, the allocated credit, and the §280C reduced-credit election.

Historical gross receipts and historical QREs must be aggregated across all group members back to the base period (1984–1988 for the regular credit), and across all open tax years group-wide — not single-entity. Acquisitions and dispositions of a trade or business since 1984 must be reflected in the fixed-base percentage. Full group history workpapers are required; a single-entity computation is a frequent exam error.

Officer wages are only includible as QREs when supported by documented time allocation to qualified research. Courts have excluded officer wages without that substantiation (Moore v. Commissioner). In multi-entity structures where officers serve several entities, written job descriptions and contemporaneous time records by business component are essential.

Yes. All records must be contemporaneous — created while the work happens. Retroactive reconstruction at tax time will not satisfy IRS examination standards. This applies across every documentation layer: ownership records, business component descriptions, time tracking, supply invoices, and third-party research contracts.

For informational purposes only. This is not tax or legal advice. Multi-entity credit computations are complex — consult a qualified tax advisor. References: IRC §41 · Treas. Reg. §1.41-6 · Form 6765 (Rev. Dec. 2024).