What is the WBSO, and what does RVO expect from your hour records?

What exactly is the WBSO?

WBSO stands for Wet Bevordering Speur- en Ontwikkelingswerk, the Dutch act promoting research and development. It isn't a grant paid into your account but a tax measure: as an employer you pay less payroll tax on the wages of staff doing R&D work. Self-employed people get an extra deduction in their income tax instead. According to RVO, the Netherlands Enterprise Agency that runs it, around 20,000 companies use it each year.

The work has to be carried out in the EU and fall into one of these types: developing new software, developing a new physical product or production process, or technical-scientific research. It has to be done in a planned way, for example in phases, and your company has to pay Dutch income tax and/or payroll tax.

What is the WBSO worth in 2026?

The benefit is a percentage of your R&D wage costs, with a higher percentage over the first bracket. For 2026 that bracket was indexed once by 2.9%, after the Dutch Senate approved the 2026 Tax Plan on 16 December 2025.

Employers that didn't use the WBSO in 2024 calculate with a fixed R&D hourly wage of €29. Self-employed people without staff get a fixed R&D deduction instead of a percentage, provided they put in at least 500 R&D hours a year.

When do you apply?

Employers can apply up to the last day of a month. The period then starts on the first of the next month and runs to 31 December. The last date to apply for 2026 was 30 September 2026. For self-employed people without staff, the period starts on the day they apply.

Applications for 2027 open from mid-November 2026 and need eHerkenning at level 3, the Dutch business login. An approved application gives you an S&O-verklaring (R&D declaration) listing the projects and hours the credit covers.

What does RVO expect from your hour records?

Your records start when the project starts. RVO asks for two things: hour records and project records, and it can ask to see both during an audit. If you claim actual costs and expenses instead of the fixed amount, you also keep a costs and expenses administration.

• Per day, per project, per employee. RVO's wording: at a minimum, separate the hours by day, by project and by employee.
• Update at least every 10 working days. Update the number of realised R&D hours in your own records at least every 10 working days.
• No hours on sick or leave days. Don't write R&D hours for employees who are ill or on leave. RVO can check this against your absence records.
• Your own system is fine. RVO offers an Excel template, the ‘Model urenstaat WBSO’, but you may use your own time tracking.
• Project records alongside. Documents showing what you did technically and how the project progressed, bundled per project, with date and author. Ready within two months after each calendar quarter ends, and kept for seven years.

What do you do after the year ends?

Everyone with an R&D declaration reports the realised R&D hours each year by 31 March of the following year, plus costs and expenses where they apply. This is the mededeling S&O-realisatie. You file it even if you realised zero hours. The exception is a self-employed person without staff who realised more than 500 R&D hours.

Filing late means a fine. If you don't file at all, RVO assumes zero R&D hours after a reminder: you repay the entire payroll tax reduction, plus a fine. Hour records that are right throughout the year turn this report into simple addition.

What changes in 2027?

On 15 September 2026 RVO announced what's proposed for 2027. The rates and the first bracket stay the same: 36%, 50% for starters and 16%, with a first bracket up to €391,020. The fixed R&D hourly wage goes from €29 to €33.

These changes are final only once the Dutch Senate approves them. RVO publishes the WBSO 2027 manual (Handleiding WBSO 2027) from November 2026. Check the numbers there before you apply.