Expenditures eligible for the CIR: complete guide 2026

Update April 2026 - The research tax credit (CIR) represents more than 6 billion euros in annual support for innovation by French companies. But its effectiveness depends on a simple point: the quality of the declared base. Knowing how to identify CIR eligible expenses is the key to maximizing your tax credit while remaining compliant with tax doctrine.

In 2026, the BOFiP doctrine updated on August 13, 2025 (BOI-BIC-RICI-10-10) remains the reference for determining which research expenses are included in the calculation of the CIR. This guide details each eligible category, the applicable rates and the most common pitfalls identified during tax audits.

Quick answer: CIR eligible expenses include research personnel expenses (researchers, technicians), depreciation allocations for R&D equipment, operating expenses (calculated at a flat rate of 43% of personnel expenses and 75% of depreciation), research operations outsourced to approved organizations (capped at €10 million or twice internal expenses), as well as defense and protection costs. patents and technological monitoring. The CIR rate is 30% up to €100 million in expenses and 5% beyond.

The CIR is governed by article 244 quater B of the General Tax Code. It concerns industrial, commercial and agricultural companies taxed according to their actual profit, which incur research and development expenses.

The mechanism is as follows:

• 30% of research expenses up to 100 million euros;
• 5% of expenses exceeding this ceiling.

For a company declaring €500,000 of eligible research expenses, the tax credit therefore amounts to €150,000 (500,000 × 30%). This amount is deducted from the corporate tax due. If the CIR exceeds the IS, the balance is refundable for SMEs in the Community sense (less than 250 employees, turnover < €50 million or balance sheet < €43 million). For other companies, the surplus can be carried forward over three financial years.

Eligible activities are divided into three categories defined by the Frascati manual, taken up by the BOFiP doctrine:

• Fundamental research: experimental or theoretical work without specific practical application;
• Applied research: investigations aimed at acquiring new knowledge with a view to a specific application;
• Experimental development: systematic work based on existing knowledge to manufacture new materials, products or processes.

Point of vigilance: Classic iterative development (incremental improvement of an existing product) does not generally fall under the CIR. It is necessary to demonstrate the presence of unresolved technological obstacles and an experimental approach.

Personnel expenses in practice constitute the first item in the research tax credit base. They often represent 60 to 80% of the declared total.

Who is affected?

May be taken into account the remuneration of people directly participating in R&D projects:

• Researchers: executives or experts designing and directing research work;
• Research technicians: personnel contributing to the experimental implementation of projects;
• Research project management staff: project managers, laboratory managers;
• Technical support staff: scientific librarians, research equipment maintenance technicians.

What remuneration should be included?

The base includes all of the following elements, in proportion to the time devoted to research operations:

• gross wages and salaries;
• benefits in kind;
• end-of-career compensation;
• legal and conventional social contributions (employer share);
• profit-sharing and participation;
• stock options and free share allocations (under the conditions provided for by the CGI).

The rule of time traceability

This is the most sensitive point during a tax audit. The company must be able to justify the share of each employee's time allocated to R&D. Tools accepted by the administration include:

• individual or collective timesheets;
• project reports;
• employment contracts specifying the research mission;
• functional organization charts per project.

Concrete example: An ESN with 120 employees assigns 15 engineers to an R&D project on algorithmic optimization. Time spent is tracked via a project management tool with weekly allocation. If these 15 engineers devote on average 70% of their time to the eligible project, only 70% of their remuneration is included in the CIR base.

Allocations to depreciation of tangible assets allocated to research are eligible, under certain conditions.

Property concerned

• Equipment and tools: test machines, prototypes, calculation servers, measuring instruments;
• Buildings: only in the proportion of their surface area allocated to research (doctrine limits this consideration).

Specific rules

• Only economic depreciation (linear depreciation) is retained;
• For goods used partially for research, only the share of use is eligible;
• Assets depreciated on a decreasing basis are subject to restatement.

Practical case: A biotech startup acquires a mass spectrometer for €250,000, amortized linearly over 5 years. The annual allocation of €50,000 enters entirely into the CIR base if the device is exclusively dedicated to R&D.

Operating expenses are not declared in reality. They are calculated as a flat rate, which constitutes a significant advantage for declarants:

• 43% of research personnel expenses;
• 75% of eligible depreciation allocations.

This package covers all indirect costs: laboratory supplies, energy, scientific documentation, publication costs, travel linked to research projects. No additional supporting documentation is required for these fixed expenses, which considerably simplifies the preparation of the file.

Illustration: For €300,000 of personnel expenses and €60,000 of eligible depreciation, the fixed operating expenses amount to (300,000 × 43%) + (60,000 × 75%) = 129,000 + 45,000 = €174,000. The total base then reaches €534,000, generating a CIR of €160,200.

Expenses entrusted to third parties are eligible, but their treatment is strictly governed by the BOFiP doctrine (BOI-BIC-RICI-10-10-20-30).

Eligible providers

• Public research organizations (universities, CNRS, Inserm, CEA, etc.);
• Higher education establishments;
• Research project umbrella companies approved by the Ministry of Research;
• Qualified individual experts (up to 10% of the total amount of outsourced expenses).

Applicable ceilings

Outsourced expenses are taken into account within the limit of the lower of the following two amounts:

• 10 million euros;
• 2 times the company's internal research expenses.

Important: A company that does not carry out any R&D operations internally cannot base its entire CIR declaration on outsourced expenses. The doctrine requires direct involvement of the declarant in the research work.

Billing and documentation

Each invoice must precisely detail:

• the nature of the research work entrusted;
• the link with the R&D projects of the client;
• the cost corresponding to each operation. A written agreement must govern the relationship between the principal and the service provider, specifying in particular the intellectual property of the results.

Beyond the main positions, several complementary categories enrich the CIR base:

Patent defense and protection costs

Expenses related to the filing and protection of invention patents are eligible, up to a limit of €60,000 per year and per company. This includes:

• filing fees with the INPI or the EPO;
• industrial property consultancy fees;
• translation costs for international extensions.

Costs for defending litigation (counterfeiting, patent invalidity) are, however, not eligible.

Technology monitoring

Scientific and technological monitoring expenses are taken into account within the limit of €60,000 per year. Are concerned:

• subscriptions to scientific databases;
• participation in conferences and professional fairs;
• subscription fees to specialized journals.

Standardization and drafting of standards

Expenses incurred as part of participation in standardization commissions are eligible, provided that the work aims to establish technical standards linked to the company's R&D activities.

Innovation subcontracting (CII) expenditure

Be careful not to confuse CIR and Innovation Tax Credit (CII, article 244 quater C of the CGI). The CII concerns expenses for the design of prototypes and pilot installations of new products, without research requirements within the meaning of Frascati. The CII rate is 20% (since January 1, 2023), with a spending ceiling of €400,000 for SMEs, i.e. a maximum credit of €80,000. A company can combine CIR and CII on separate projects.

The tax administration examines CIR declarations with particular attention. Here are the most common reasons for rejection observed during checks:

• Wrong classification of work: iterative development or adaptation of existing solutions wrongly classified as experimental research;
• Absence of scientific justification: the technical file does not demonstrate the existence of technological obstacles nor the experimental approach;
• Insufficient time traceability: no hourly allocation or undocumented overall estimates;
• Unqualified service provider: subcontractor not having ministry approval or not falling within the categories provided for by the CGI;
• Operating expenses declared as actual instead of the flat rate;
• Missing contractual documents: absence of written agreement with the service provider or non-detailed invoices.

Hayot Expertise Advice: A good CIR does not only defend itself with an amount. It defends itself with a rigorous scientific method, a complete technical file and a clean tax base. The CERFA technical notice n°2006 (revised) details the requirements of the supporting file to be kept.

The CIR can be combined with several innovation aids:

• Young Innovative Company Status (JEI): exemptions from social charges and income tax, cumulative with the CIR subject to compliance with de minimis aid ceilings;
• Public subsidies: subsidized expenses are excluded from the CIR base, but the remainder remains eligible;
• Innovation tax credit (CII): accumulation possible on separate operations;
• Collaborative research system (article 244 quater B-3° of the CGI): rate increased by 50% for research expenses entrusted to public organizations within the framework of structured partnerships.

To broaden the reflection, see also New tax measures in 2026, our guide Business financing 2026 and the pillar page Taxation 2026.