Have my WBSO file reviewed Help with an RVO audit
BY PETER KLAREN · LAST REVIEWED SEPTEMBER 2026 · SOURCE: WBSO GUIDE 2026 (RVO)
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What does RVO check? Desk-based review or visit Which documents? Hours requiring attention Software projects Product, process and technical-scientific research How do you prepare? RVO-proof file check Correspondence with the application Correction and fine Self-employed professionals and 500 hours RVO or Belastingdienst? Object within 6 weeks Frequently asked questions
What does RVO check during a WBSO audit?
RVO performs retrospective audits at companies that have received an S&O-verklaring. The core of the assessment is: does the application correspond with actual practice, and can this be demonstrated?
| Component | What does RVO examine? |
|---|---|
| Application | Do the activities performed correspond with what was approved? |
| Project records | Can the nature, content and progress of the R&D be demonstrated? |
| Hours registration | Who worked when, for how many hours and on which project? |
| Holiday and sickness | Do the registered R&D hours logically correspond with these records? |
| Actual costs | Were the costs awarded in advance, incurred and paid? |
| Actual expenditures | Are the investment, use and R&D attribution substantiated? |
| Realisation | Do the reported hours and costs correspond with the records? |
An RVO audit is not about creating a perfect file retrospectively, but about a credible and verifiable connection between what you applied for, what was technically performed in practice, which hours and costs belong to it and what was ultimately realised.
Desk-based review or on-site audit
RVO can conduct the WBSO audit remotely or at your business premises. You receive advance notice of the audit, the information RVO wants to receive and the deadline for providing it.
| Desk-based review | On-site visit |
|---|---|
| Submit documents digitally | Audit at the business location |
| Assessment of records remotely | Records plus substantive explanation |
| Additional questions possible | Technical employees can provide explanations |
| Preparing the file is central | Both the file and interviews are important |
In both cases, the audit is announced in advance. You therefore know which documents must be provided and when.
Which documents can RVO request during an audit?
The relevant documents differ by project. Above all, the file must convincingly show what actually happened.
Administration
hours registration project records statement of realisation S&O-verklaring(en)
Technical evidence
technical drawings test and measurement reports photographs of prototypes calculations technical emails Git commits and pull requests Jira/GitHub issues benchmark results research reports
For actual costs and expenditures
invoices proof of payment quotations order confirmations substantiation of equipment attribution
More for each record type: hours registration, project records and costs and expenditures.
Which hours are often a point of attention?
Job title is not decisive. A director or project manager may only record R&D hours to the extent that they personally perform substantive technical R&D activities within the approved project.
RVO looks at the activities actually performed, not the role on paper. Employees who are not substantively involved in the technology — for example marketing or secretarial staff — do not generate R&D hours.
No R&D hours
general management planning and coordination administration commerce and sales organisational activities marketing secretarial work
For the complete rules, see WBSO hours registration.
Software projects during an RVO audit
For software projects, Git history, issues, technical designs, benchmarks and test results can be very important evidence.
However, a large number of commits does not in itself prove that R&D took place. It must also be clear which programming-technical bottleneck was solved and how the technical development progressed.
See also WBSO software and project records for software.
Product, process and research projects during an audit
Product development
Designs, changes, calculations, prototype logs and test reports make the development process visible.
Process development
Process measurements, trial-run reports and settings show which technical uncertainty was resolved.
Technical-scientific research
Research design, measurement series, interim findings and results together form the research trail.
How do you prepare for a WBSO audit?
- 1 Compare the application and S&O-verklaring — Which activities were specifically approved?
- 2 Check the hours registration — Per person, project and day; within the 10-working-day rule; consistent with holiday and sickness records.
- 3 Check the technical file — Can the development or research be followed chronologically?
- 4 Check actual costs and expenditures — Invoices, payments, direct attribution and serviceability.
- 5 Compare with the statement of realisation — Were the same totals and projects used?
- 6 Identify deviations in advance — Why did hours, technical approach or planning differ? A good explanation beforehand is stronger than a surprise during the audit.
- 7 Make sure someone with technical project knowledge is available — Substantive questions are best answered by someone who actually performed the work.
RVO-proof file check: can you answer these seven questions with “yes”?
- Is it clear per project what was done technically?
- Do the hours correspond with technical progress?
- Are documents dated and traceable to the author?
- Have failed solution approaches also been retained?
- Do the hours correspond with sickness and holiday data?
- Can actual costs and expenditures be demonstrated as paid?
- Does the statement of realisation correspond with the records?
If one of these answers is “no”, that is a potential audit point. Preferably resolve it before RVO asks about it.
Correspondence with the approved R&D activities
The activities actually performed must recognisably correspond with the approved R&D project.
This does not mean that every experiment must proceed exactly as stated in the application. New technical bottlenecks, failed solution approaches and changes during development are not unusual — they are part of R&D. The file must, however, clearly show that the work remained within the approved technical development or research direction.
What happens if RVO finds deviations?
If the audit shows that WBSO requirements or administrative obligations were not met, RVO can issue a corrective S&O-verklaring. This can reverse all or part of the S&O payroll tax reduction previously granted.
| Consequence | Explanation |
|---|---|
| Corrective S&O-verklaring | The correction can be up to the originally awarded S&O payroll tax reduction |
| Fine | Depending on the breach found, RVO can impose a fine |
| Processing | The fine is included in the corrective S&O-verklaring |
More about corrections: report WBSO realisation.
WBSO audit for self-employed professionals
For self-employed professionals, the 500-hour requirement is particularly important. If an audit shows that fewer than 500 qualifying R&D hours were realised, RVO withdraws the S&O-verklaring.
RVO audit or Belastingdienst audit?
These two audits are not the same and are carried out by different authorities.
| RVO checks | Belastingdienst checks |
|---|---|
| The substance of the R&D project | Payroll tax and tax returns |
| R&D hours realised | Tax offsetting |
| Project records | Correct processing of the decision |
| Actual costs and expenditures | Tax treatment |
Disagree with a correction or fine?
You can object within 6 weeks after the date the corrective S&O-verklaring and/or fine was sent.
Important: you must process the corrective S&O-verklaring while the objection procedure is ongoing. An objection does not automatically suspend that processing.
→ Everything about WBSO objections → Received additional questions from RVO?
Frequently asked questions about RVO WBSO audits
How does an RVO WBSO audit work?
The audit can take place at your business location or as a remote desk-based review. RVO announces the audit in advance and tells you which information is required and by what date it must be submitted.
What exactly does RVO check for WBSO?
Whether the application corresponds with the actual activities, how many R&D hours were actually spent and — where actual costs and expenditures were chosen — which amounts were incurred and paid.
Which records must I be able to show?
Hours registration and project records and, for actual costs and expenditures, also records of costs and expenditures with invoices and proof of payment.
Does RVO always visit for an audit?
No. A WBSO audit can also be conducted entirely remotely as a desk-based review.
Can RVO correct WBSO that has already been awarded?
Yes. RVO can issue a corrective S&O-verklaring up to the amount of the originally awarded S&O payroll tax reduction.
Can RVO impose a fine?
Yes, depending on the breach identified. The fine is included in the corrective S&O-verklaring.
What if a self-employed professional realised fewer than 500 hours?
RVO then withdraws the S&O-verklaring.
How long do I have to object?
Six weeks from the date the corrective S&O-verklaring or fine was sent. In the meantime, you must still process the correction.
RELATED PAGES
WBSO administration → WBSO hours registration → WBSO project records → WBSO costs and expenditures → Report WBSO realisation → RVO additional questions → WBSO objection → WBSO requirements →
Has RVO announced a WBSO audit?
We review your file in advance, compare the application, hours, project records and realisation, and help identify any weaknesses before the audit.
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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.