Research Tax Credit and Tax Audits: How to Secure Your Filing in 2026

But it is also one of the most audited tax incentives.

Many business owners only start asking questions after filing. The right approach is to ask them beforehand and plan your CIR filing as your projects progress.

So how do you secure your CIR filing in case of a tax audit? Here are the key points to anticipate.

Understand that the audit primarily focuses on the scientific substance

A CIR audit is not limited to the amounts declared. The tax authorities primarily verify:

• The reality of the research work
• The existence of a scientific barrier or technical uncertainty
• The experimental approach through iteration
• The consistency between objectives and results

If the scientific qualification is weak, the rest of the filing is too.

The first step in securing your position is therefore to document your work precisely.

Build a robust technical file from the year of filing

The supporting documentation should not be written after the fact.

It must demonstrate:

• The scientific and technological context
• The existing state of the art (patents, publications)
• The uncertainties encountered
• The hypotheses tested
• The experiments conducted
• The conclusions reached

The more structured your demonstration, the more defensible it is.

Reconstructing these elements three years later is always more complex.

Secure the traceability of R&D time

Salaries often represent the largest portion of the CIR.

In the event of an audit, the tax authorities may request:

• Job descriptions
• Employment contracts
• Timesheets
• The breakdown of assignments

An employee declared at 80% R&D must be able to concretely justify that allocation.

The absence of precise tracking immediately weakens the calculation.

Verify subcontracting compliance

Subcontracting is one of the most frequently examined areas.

You must in particular:

• Verify the accreditation of service providers
• Retain the contracts
• Justify the exact nature of the work performed
• Avoid overlaps with your internal teams

Poorly managed subcontracting can lead to a partial challenge of the tax credit.

Anticipate the dialogue with the tax authorities

A CIR audit may involve:

• The tax administration
• Experts from the Ministry of Research

The ability to clearly explain your work is decisive.

A file that is too technical without clear explanations may be misunderstood. A file that is too simplified may be deemed insufficient.

The balance between scientific rigor and clarity is essential.

The most common mistakes we encounter

Among innovative companies, we regularly observe:

• An insufficiently argued R&D qualification
• Poorly allocated expenses
• Incomplete documentation
• An approach that is too fiscally driven and not technical enough
• Filing preparation done in a rush when an audit occurs

Result: stress, prolonged exchanges with the tax authorities, or even partial reassessment and penalties.

Should you request a tax ruling?

A tax ruling (rescrit fiscal) can in certain cases be a useful tool, as it allows you to consult the tax authorities in advance on the eligibility of a specific project.

This approach:

• Secures your position
• Provides official validation
• Reduces uncertainty in case of a future audit

It is not systematic, but can be strategic for complex projects.

Our approach at Fifty Bees

At Fifty Bees, we believe that securing the CIR starts before the filing.

Specifically, we support you in:

• Scientifically qualifying your projects
• Structuring the technical documentation
• Implementing rigorous R&D time tracking
• Verifying subcontracting compliance
• Preparing a defensible file in case of an audit

Goal: fund your innovation without exposing your company to disproportionate tax risk.

Want to secure your CIR before an audit?

A discussion allows you to:

• Assess the robustness of your filing
• Identify areas of vulnerability
• Implement corrective measures if necessary

The CIR is a strategic lever. It deserves preparation that matches its financial impact.

Let’s talk to structure your approach and confidently anticipate any audit.