Navigating the “Substantially All (Process of Experimentation)” Test for the Indiana R&D Tax Credit

The “Substantially All” test requires that 80% or more of the activities for a given research project (business component) must involve a systematic process of experimentation. This ensures the project attempts to resolve technical uncertainty through structured trial, error, modeling, or simulation, rather than relying on routine engineering or common knowledge.

This criterion, codified under federal law and adopted by the State of Indiana, is the final and often most critical hurdle in qualifying expenditures for the Indiana Research Expense Credit (IC 6-3.1-4). Compliance necessitates strict adherence to federal standards and meticulous, contemporaneous documentation to successfully withstand state audit scrutiny by the Indiana Department of Revenue (DOR).

I. Statutory and Regulatory Foundations of Qualified Research

The State of Indiana actively incentivizes investments in innovation through the Research Expense Credit, established under Indiana Code (IC) 6-3.1-4-1.1 The core mechanism for defining eligible activities and expenses relies heavily on federal statute. Indiana defines Qualified Research Expenses (QREs) by direct reference to Section 41(b) of the Internal Revenue Code (IRC), specifically as that section was in effect on January 1, 2001.2

This statutory conformity means that to claim the Indiana credit, taxpayers must satisfy the rigorous Four-Part Test mandated by federal law for all claimed research activities.

A. The Federal Four-Part Test (IRC § 41(d))

All four criteria must be satisfied simultaneously for research related to each product, process, or other business component 2:

1. Section 174 Requirement: The costs associated with the activity must be treated as research or experimental expenditures under IRC Section 174.5
2. Discovery Test (Technological Uncertainty): The activity must be undertaken for the purpose of discovering information that is technological in nature.5 This requires the identification of an underlying technological uncertainty—the taxpayer must demonstrate they could not know the outcome or method of achieving the desired result prior to the research.6
3. Business Component Test: The application of the discovered information must be intended to be useful in the development of a new or improved business component of the taxpayer.5
4. Process of Experimentation (POE) Test: Substantially all of the activities must constitute elements of a process of experimentation relating to a qualified purpose, such as a new or improved function, performance, reliability, or quality.7

The technological nature of the research activities must be clearly established, as the successful execution of the POE test is often contingent upon establishing technological uncertainty. If a taxpayer fails to document the technological uncertainty—that is, demonstrating why experimentation was truly necessary—the DOR may conclude that the resulting trial-and-error was merely the routine application of “long standing techniques” or “common knowledge”.9 The ability to articulate why experimentation was required, therefore, becomes foundational to proving that the experimentation itself meets the qualifying criteria.

II. Deconstructing the “Substantially All” Test

The “Substantially All” test provides the quantitative measurement for the POE requirement, focusing on the allocation of time and resources to experimental activity for a specific business component.

A. The Quantitative Threshold: Defining 80%

The definition of “substantially all” for the research credit is explicitly defined by federal regulation, adopted by Indiana, as 80% or more.2

This 80% threshold must be applied independently to the research activities for each specific business component under development.2 The primary measurement methodology typically relies on the labor component (wages) and is measured on a cost or other “consistently applied reasonable basis”.2

A significant benefit, known as the “inclusion benefit,” arises if the threshold is met. If the taxpayer can demonstrate that 80% or more of the total activities related to a business component constitute elements of a systematic POE, then 100% of the research activities for that component are treated as Qualified Research Expenses (QREs).2 The non-experimental portion (up to 20%), such as initial design sketching or routine testing, is included.

However, tax authorities frequently utilize this strict, all-or-nothing rule to deny claims. If an auditor determines that the non-experimental activities for a component account for 21% or more of the total activity, the POE percentage drops below 80%. In such a scenario, the entire business component fails the test, and 100% of the related QREs are disallowed.10 This inherent risk compels taxpayers to implement compliance tracking designed to demonstrate a percentage safely above the 80% minimum to mitigate the threat of audit disallowance.

B. The Process of Experimentation (POE) in Detail

The POE is a systematic search intended to resolve the technological uncertainty identified in the Discovery Test.2 It necessitates a methodical evaluation of one or more alternatives to achieve a desired result—specifically relating to a new or improved function, performance, reliability, or quality.2

A valid POE must clearly demonstrate the following steps:

1. Defining Objectives: Establishing the qualified purpose (e.g., improved performance).7
2. Identifying Uncertainty: Determining the technical barriers preventing the objective’s achievement.
3. Systematic Evaluation: Implementing a structured plan involving modeling, simulation, trial and error, prototyping, or physical testing to evaluate design alternatives and variables.2
4. Recording Results: Documenting failures and successes, and modifying the approach based on the data collected.

Activities that are specifically excluded or do not constitute a POE generally fall into the non-qualifying 20% bucket, including general administrative tasks, market research, routine data collection, or the application of known scientific or engineering principles.9

III. Indiana Department of Revenue (DOR) Administrative Guidance and Case Law

The Indiana DOR’s guidance, reflected in its published rulings and handbooks, emphasizes stringent documentation and a narrow interpretation of what constitutes qualified technological research.

A. DOR Audit Practices and Published Rulings

The Indiana DOR focuses heavily on distinguishing true experimentation from routine business activities. The department has, in several administrative rulings, denied claims where taxpayers attempted to classify common industry challenges as technological uncertainty. For instance, in disputes involving certain architectural and construction activities, the DOR found that the taxpayers’ efforts were better categorized as refining and applying long standing techniques to overcome site-specific difficulties, rather than fundamentally expanding the common knowledge or existing level of information in their field.9

To successfully defend the POE test, a taxpayer must present documentary evidence of a systematic approach that includes the rejection and modification of alternatives. Rulings regarding design-build projects illustrate this requirement, requiring taxpayers to show they tested various prototypes, including different mechanical components (e.g., arms, clamps, jigs) and computer programming configurations that were specifically tested, approved, or discarded during the development process.11 The documentation of rejected alternatives is highly persuasive evidence validating the systematic nature of the POE.

B. The Critical Nexus and Documentation Requirement

The most significant vulnerability for taxpayers during an Indiana R&D audit is typically the lack of contemporaneous documentation proving the quantitative requirement of the “Substantially All” test.

Indiana statute mandates that every person subject to tax must maintain books and records sufficient for the department to determine tax liability (IC § 6-8.1-5-4(a)).11 For the R&D credit, this translates into the federal requirement to retain records necessary to substantiate the claimed credit.12

The DOR has explicitly rejected retrospective studies, noting that relying solely on the recollections of various personnel (SME interviews) gathered long after the research was complete is deficient for meeting the statutory and regulatory burden of proof.2 Auditors consistently disallow QREs when documentation fails to “demonstrate nexus between the wages and the projects claimed”.6 Without contemporaneous time tracking, the taxpayer cannot mathematically link the employee wages—which form the basis of the QREs—to the specific activities that meet the 80% threshold, leading to a complete failure of the “Substantially All” test.

The strict application of the state’s general record-keeping mandate acts as a crucial audit defense mechanism for the DOR, allowing auditors to invalidate claims purely based on procedural failure, regardless of the underlying technical merit of the research. Therefore, maintaining strict, concurrent time tracking is essential for providing the primary line of defense against audit disallowance in Indiana.

IV. Practical Compliance: Documenting the “Substantially All” Test

Successful compliance requires creating and maintaining records that clearly isolate and measure the time spent on experimental activities, establishing that the 80% threshold was met for each business component.

A. Essential Documentation Categories

Taxpayers must maintain a comprehensive set of records, directly linking payroll expenditures to the systematic process of experimentation.13

Table Title: Essential Documentation for Substantially All Compliance

B. Specific Documentation for the Process of Experimentation

To substantiate the POE, documentation must show a measurable effort to eliminate uncertainty through trial and error. Examples of high-value documentation include:

• Design Logs and Technical Notes: These documents should detail the various technical alternatives considered, the scientific or engineering principles being tested, and the specific variables under evaluation.4
• Test Protocols and Results: Records of simulations, modeling, and physical testing, including both raw data and analysis. Documentation demonstrating specific design revisions based on testing failures is particularly critical for proving the systematic nature of the POE.4
• Software Artifacts: For software development projects, information extracted from contemporary project management tools, bug tracking systems, and source code repositories (showing version changes and specific feature development) can demonstrate a continuous POE.4
• Contemporaneous Records: The documentation must be created concurrent with the activity, rather than relying on recollections. This requirement is paramount for defeating auditor challenges regarding the quantitative 80% threshold.12

V. Example Application: The Substantially All Calculation

The following example illustrates how the 80% requirement is quantified at the component level and highlights the potential risks of insufficient allocation tracking.

Scenario: Advanced Material Fabrication Process Improvement

An Indiana company develops a new fabrication process intended to increase the reliability of a critical automotive part (the business component). The key uncertainty lies in determining the precise temperature and pressure cycling required to achieve the desired structural integrity without material degradation. The R&D team spends 2,000 hours on activities related to this process component.

Analysis of the Substantially All Test:

1. POE Percentage Calculation:
   
   $$\frac{1,650 \text{ POE Hours}}{2,000 \text{ Total Hours}} = 82.5\%$$
2. Conclusion: The project meets the “Substantially All” requirement, as 82.5% is greater than the 80% threshold.2
3. Credit Inclusion: Since the threshold is exceeded, all 2,000 hours of associated employee wages are deemed Qualified Research Expenses (QREs) for this business component.

If, however, the auditor successfully challenged 51 hours of the Pilot Line Testing as routine maintenance (reclassifying them as Non-Qualifying), the POE hours would drop to 1,599 (1,650 – 51). The POE percentage would then be $1,599 / 2,000 = 79.95\%$. Since this falls below 80%, the entire project fails the “Substantially All” test, and $100\%$ of the QREs for this component would be disallowed.

VI. Strategic Context and Indiana Credit Mechanics

The requirement to pass the “Substantially All” test is the gateway to unlocking significant financial incentives offered by the state, including tiered tax rates and sales tax exemptions.

A. Indiana Research Expense Credit Calculation

Indiana offers a tiered calculation method based on the federal Regular Credit Method, focusing the highest rate on the first $1 million of expenditures above the established base amount.

Table Title: Indiana Research Expense Credit Calculation Tiers

The credit is nonrefundable but highly valuable, offering a robust 10-year carryforward period to ensure that businesses, particularly those in high-growth or startup phases, can utilize the benefits against future tax liability.1

B. Industry Focus and Risk Concentration

Indiana strategically targets incentives toward R&D-intensive industries, including Manufacturing, Life Sciences, Software Engineering, and Aviation & Aerospace.14 Research-intensive sectors such as pharmaceuticals, aircraft, and computer/electronic products are prime examples of the targeted activities.15

An analysis of credit usage reveals a critical audit concentration: corporate taxpayers claim approximately 63% of the total credits awarded, yet they represent only 10% of the total claimants.16 This data indicates that the majority of the credit value flows to a small number of large, R&D-heavy corporations. Tax authorities, seeking to maximize audit efficiency, naturally prioritize reviews of high-value returns. Consequently, large corporate claimants operating in these targeted sectors face an exponentially higher risk of deep scrutiny by the DOR. For these entities, achieving perfect compliance with the “Substantially All” quantitative standard is a critical component of their overall risk management strategy. A case study involving an Indianapolis biotech firm illustrates the magnitude of these incentives, where the company qualified for over $282,000 in Indiana state R&D credits over a four-year period.17

C. Secondary Compliance Risk: R&D Sales Tax Exemption

In addition to the income tax credit, Indiana offers a 100% sales and use tax exemption for depreciable tangible personal property used directly and exclusively in qualified research and development.1

The eligibility for this exemption is entirely predicated upon the underlying activity meeting the definition of “qualified research” defined by IRC § 41.2 If the DOR successfully challenges an R&D Income Tax Credit claim because the taxpayer failed to prove the 80% “Substantially All” threshold, that same finding can be used to invalidate the sales tax exemption on all equipment purchased for that project. This failure results in a secondary financial consequence: the risk of a retroactive assessment of sales tax on the previously exempted property, significantly compounding the financial penalty of non-compliance.

VII. Conclusion: Strategic Compliance and Audit Defense

The rigorous application of the “Substantially All (Process of Experimentation)” test by the Indiana Department of Revenue confirms that research qualification is both a technical and a documentation challenge. For businesses seeking the Indiana R&D Tax Credit, success hinges on demonstrating that the research activity systematically moved beyond routine engineering and that this effort can be substantiated through clear records.

Strategic compliance requires proactive measures to ensure documentary evidence can defend the 80% threshold under intense scrutiny:

1. Contemporaneous Documentation: Taxpayers must establish robust, centralized systems for capturing employee time and project expenditures concurrently with the research activity. Relying on retrospective studies or employee recollections is consistently cited as a fatal flaw by the DOR.2
2. Establishing Technical Nexus: All QREs, particularly wages, must be directly linked (a nexus must be established) to the specific steps of the systematic experimentation process. Documentation must clearly delineate experimental time from routine tasks to satisfy the DOR’s requirement for proof of the 80% metric.6
3. Proving the Process: Documentation must not only state that alternatives were tested but must detail which alternatives were pursued, why they were chosen, and the results of the trials, demonstrating the intentional pursuit of technical information to resolve technological uncertainty.11

By adhering strictly to the quantitative demands of the 80% rule and the qualitative necessity of systematic technical documentation, businesses in Indiana can effectively substantiate their claims, maximize their Research Expense Credit utilization, and successfully mitigate significant state audit risks, including the dual exposure to income tax credit disallowance and sales tax reassessment.

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