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Reduce up to 80% of the wage withholding tax on your eligible R&D researchers — one of Belgium’s most impactful federal tax incentives for innovation-driven companies.
Leyton’s specialists help Belgian companies identify qualifying researchers and projects, manage BELSPO notification and ensure full compliance under the latest 2025 guidelines.
How it works
The Partial Withholding Tax Exemption for R&D allows Belgian employers to retain 80% of the wage withholding tax deducted from the salaries of eligible researchers — rather than paying it to the Belgian Treasury.
The measure is laid down in Article 275/3 of the Belgian Income Tax Code. This federal incentive applies to companies of all sizes and sectors performing qualifying R&D activities in Belgium, in line with the definitions of the OECD Frascati Manual.
Following stricter Supreme Court case law and updated BELSPO guidelines effective from January 2025, the notification requirement has been significantly tightened: R&D projects must be formally registered with BELSPO before their actual start date.
Projects notified after their start date no longer qualify for the exemption.
Eligible R&D activities include:
Eligible companies include:
How we help
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Clients supported worldwide
Years of expertise in R&D tax incentives
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Tax, financial and technical experts including PhDs and scientific advisors
How it helps
Discover what profiles and activities qualify for the R&D withholding tax exemption.
OUR PROCESS
A structured approach ensures every qualifying researcher and project is correctly identified, registered and maintained — with full audit-readiness at every stage.
Review your company structure, project portfolio and R&D roles to identify all activities and researchers potentially qualifying for the partial withholding tax exemption.
Assess the full potential saving across your eligible researcher population and R&D project scope, and model the expected annual benefit.
Map and classify all qualifying R&D activities in line with the OECD Frascati Manual definitions required by BELSPO and the Belgian tax authorities.
Prepare and submit complete, compliant BELSPO registration files — including project descriptions, start and end dates, and researcher qualification evidence — before R&D activities begin.
Integrate the exemption into your monthly or quarterly withholding tax declarations via Form 274 and establish time registration procedures for qualifying researchers.
Provide full support during tax authority controls, monitor BELSPO guideline updates and manage renewals and periodic updates across subsequent payroll periods.
WE ARE HERE TO HELP
Ready to reduce your payroll tax costs and maximise your R&D funding in Belgium?
Book a free assessment with one of Leyton’s Innovation Incentive specialists and estimate your potential annual savings under the Partial Withholding Tax Exemption for R&D.
WE ANSWER YOUR DOUBTS
Everything you need to know about Partial Withholding Tax Exemption for R&D before working with us.
The Partial Withholding Tax Exemption for R&D allows Belgian employers to retain 80% of the wage withholding tax deducted from eligible researchers’ salaries — rather than transferring it to the Belgian Treasury. It is governed by Article 275/3 of the Belgian Income Tax Code and applies to companies of all sizes performing qualifying R&D activities.
Up to 80% of the wage withholding tax on eligible researchers’ salaries can be retained. The exemption applies only pro rata to the time each researcher spends on qualifying R&D activities — not to their full salary if they also perform non-R&D work.
Belgian companies and foreign companies with a Belgian establishment that employ researchers on the Belgian payroll and perform qualifying R&D activities. Eligible researchers must hold a PhD, master’s or bachelor’s degree in an exact or applied scientific field and spend at least 80% of their working time on qualifying R&D. From 2026, employees without a qualifying diploma may also qualify within a BELSPO-recognised research programme.
Qualifying activities include fundamental research, industrial research and experimental development, as defined by the OECD Frascati Manual. Activities must be part of a project or programme formally registered with BELSPO before their start date.
Yes — this is an absolute condition. Following the Belgian Supreme Court ruling of January 2023 and updated BELSPO guidelines effective January 2025, R&D projects must be notified to and registered with BELSPO strictly before their actual start date. Projects notified after commencement no longer qualify for the exemption.
A valid BELSPO notification must include a description of the project demonstrating its R&D objective, the expected start and end date, and confirmation that activities have not yet begun. Incomplete or incorrectly dated notifications are a leading cause of audit disputes and exemption denial.
Yes. The partial withholding tax exemption for R&D can be used alongside the Innovation Income Deduction (IID) and the Investment Deduction — allowing companies to build a comprehensive, layered fiscal strategy across their full R&D and innovation investment cycle.
The Belgian tax authorities have significantly increased audit activity on this measure, focusing on BELSPO notification timing, project descriptions, researcher qualifications and time registration. Leyton provides full audit support — preparing documentation packages and managing dialogue with the tax authorities to defend your claim.
Leyton manages the full process — from identifying qualifying researchers and R&D projects, to preparing Frascati-compliant BELSPO notification files, integrating the exemption into your payroll declarations via Form 274, and providing complete audit defence support. Our team stays continuously updated on BELSPO guidelines and Belgian tax authority guidance, ensuring your claim is maximised and fully compliant at every stage.