WBSO deadlines 2026: when should you apply?

BY PETER KLAREN · SOURCE: RVO WBSO GUIDE 2026

NEXT DEADLINE · 30 September 2026

Next WBSO deadline: 30 September 2026

Do you still want to use WBSO for October, November and December 2026? Submit your application no later than 30 September 2026. This applies to employers and self-employed professionals who still want to start an application period in 2026.

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Deadlines 2026 and 2027 Employers Self-employed professionals Initial application without a prescribed form Number of applications Applying for 2027 Reporting realisation Frequently asked questions

WBSO deadlines for 2026 and 2027 at a glance

The correct deadline depends on your business type and desired start date. Employers always start on the first day of a month; for self-employed professionals, the period starts on the day the application is submitted.

For the substantive application steps, see applying for WBSO; for annual parameters, see WBSO 2026.

When must an employer apply for WBSO?

For employers and other S&O withholding agents, the main rule is: submit the application no later than the last day of the month before the desired start month.

For example, if you want to use WBSO from 1 July, the application must be submitted no later than 30 June. The application period starts on the first day of the following month and automatically runs through 31 December.

An application period must last at least three months. Therefore, 30 September is the final regular submission date within the calendar year. For a start on 1 January, the exceptional deadline is 20 December.

WBSO deadline for self-employed professionals

For self-employed professionals, the application period works differently. The WBSO period starts on the day you submit the application and runs through 31 December.

A minimum application period of three months also applies to self-employed professionals. Therefore, 30 September 2026 is the final date on which you can still apply for WBSO for 2026. If you want to use the scheme from the beginning of 2027, submit an application no later than 1 January 2027.

For the eventual S&O deduction, at least 500 R&D hours and the tax hour criterion of 1,225 hours also apply. Check the other WBSO requirements.

Deadline close? Consider an initial WBSO application without a prescribed form

If you cannot complete the full technical WBSO application before the deadline, RVO allows you to submit an initial application without a prescribed form and supplement it later. This can prevent future R&D activities from falling outside the application period.

Important: if you ultimately decide not to proceed with the application, withdraw the initial application. Otherwise, for withholding agents it counts towards the maximum of four applications per calendar year.

Help with an application before the deadline

How often can you apply for WBSO?

Withholding agents can submit a maximum of four WBSO applications per calendar year. There is no maximum number of applications for self-employed professionals.

If you expect new projects or more R&D hours or costs later in the year, an additional WBSO application may be required. Describe new technical activities in advance and align the planning with the remaining application opportunities. “Submit early and expand without limit later” is therefore not a correct rule of thumb.

After submission, RVO may ask for clarification. See what to expect from RVO's additional questions.

Applying for WBSO for 2027

If, as an employer, you want to use WBSO from 1 January 2027, submit your application no later than 20 December 2026. For self-employed professionals, the application period starts on the date of submission; anyone wishing to use the scheme from 1 January 2027 should submit no later than 1 January 2027.

The announced percentages and amounts for 2027 are not yet final and remain subject to parliamentary approval. The application planning for a 1 January start is already relevant. See WBSO 2027 →

Report WBSO realisation for 2026: no later than 31 March 2027

Did your company use WBSO in 2026? Then 31 March 2027 is an important next deadline.

Withholding agents report the R&D hours realised and, where applicable, the actual costs and expenditures. Self-employed professionals submit a realisation report when they have realised fewer than 500 R&D hours.

Everything about reporting WBSO realisation → Maintain complete WBSO records throughout the year.

Frequently asked questions about WBSO deadlines

What is the final WBSO deadline in 2026?

30 September 2026 is the final regular submission date for an application period that still runs for at least three months in 2026.

When must I apply for WBSO for 1 January 2027?

Employers must submit no later than 20 December 2026. Self-employed professionals who want to start from the beginning of 2027 must submit no later than 1 January 2027.

Can I apply for WBSO retrospectively?

No. WBSO must be applied for in advance. Activities outside the granted application period do not count.

Can I still apply for WBSO for 2026 after 30 September?

Not for a new application period that must still meet the minimum duration of three months in 2026.

How often can I apply for WBSO?

Withholding agents can apply a maximum of four times per calendar year. There is no maximum number of applications for self-employed professionals.

What if I miss the deadline?

If the full application is not yet ready, an initial application without a prescribed form may be relevant. It must be submitted on time and supplemented later.

When must I report WBSO realisation for 2026?

No later than 31 March 2027.

Deadline close? Have your WBSO application reviewed

We review the technical substantiation, application period and submission planning before the deadline expires.

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SOURCES AND SUBSTANTIVE REVIEW

RVO — WBSO Guide 2026

Reviewed by Peter Klaren, WBSO specialist since 2004. Last substantively updated: 21 September 2026.