Have my WBSO records reviewed Prepare for an RVO audit
BY PETER KLAREN · LAST REVIEWED SEPTEMBER 2026 · SOURCE: WBSO GUIDE 2026
WBSO administration at a glance
| Records | What do you record? | When to update? |
|---|---|---|
| Hours registration | Hours per person, per project, per day | Within 10 working days |
| Project records | Technical activities, bottlenecks, progress and results | No later than 2 months after each quarter |
| Costs/expenditures records | Actual realised and paid costs and expenditures per project | Up to date when submitting the statement of realisation |
| Retention requirement | Complete R&D records | Retain for 7 years |
These deadlines follow from the WBSO Guide 2026. Below you can read what RVO requires for each type of record.
ON THIS PAGE
Overview and deadlines Hours registration Project records Costs and expenditures Everything must correspond From when? How long to retain? Examples of documentation If records are inadequate Are your records RVO-proof? Realisation and audit Frequently asked questions
WBSO hours registration
Record, for each employee, project and day, how many R&D hours were worked. Only hours worked by your own employees on approved R&D activities may be included.
The registration must be updated within ten working days and correspond with holiday and sickness records. An hours record reconstructed afterwards does not meet this requirement.
Everything about WBSO hours registration →
What must WBSO project records contain?
The project records must show which R&D activities were actually carried out, which technical bottlenecks occurred, which solution approaches were investigated and how the project progressed technically.
For technical-scientific research, the records must instead show how the research was designed and carried out and what the results were.
RVO lists possible supporting documents including reports, drawings, emails, photographs of prototypes, test results, measurement reports and calculations. For software, version-control and issue-tracking systems such as Git and Jira may form part of the records.
What good project records should look like
- organised per project;
- dated and traceable to the employees involved;
- technical progress is visible;
- retain failed or abandoned solution approaches as well;
- consistent with the approved application;
- updated at least quarterly, no later than two months after the end of the quarter.
Everything about WBSO project records →
Records of costs and expenditures
If you opted for actual costs and expenditures, you must be able to demonstrate per R&D project which costs and expenditures were actually incurred and paid. Keep, for example, quotations, order confirmations, invoices and proof of payment.
Only costs and expenditures applied for and granted in advance can be included. The records must also show that they are directly attributable to the R&D and satisfy the applicable serviceability requirements.
If you chose the hourly costs-and-expenditures allowance, separate cost records for WBSO are not required.
Everything about WBSO costs and expenditures →
The most important rule: everything must correspond
WBSO application ↓ approved projects ↓ project records ↔ hours registration ↔ cost records ↓ statement of realisation
RVO must be able to follow that the technical activities applied for were actually carried out, by which employees, for how many hours and — where applicable — at which actual costs.
Good WBSO records tell one consistent technical story: what you applied for, what your people actually developed or investigated, how much time was spent on it and what was ultimately realised.
From when must you maintain WBSO records?
| Situation | Start of record-keeping obligation |
|---|---|
| Self-employed professionals / S&O taxpayers | From the start date of the application |
| Employers / S&O withholding agents | From the start month of the application |
Do not wait until the S&O-verklaring arrives before you start recording; the record-keeping obligation runs from the start of the granted period.
How long must you retain WBSO records?
The complete R&D records must be retained for 7 years.
Make sure that digital systems, version history, tickets and technical documents also remain accessible and traceable after migrations. RVO explicitly points out that dates and names must be preserved, for example when migrating a version-control system.
Examples of good project documentation
Machine development
Application: development of a positioning mechanism with ±0.05 mm accuracy.
Records: technical drawings → measurement results → identified deformation → alternative bearing design → test setup → test results → new solution approach.
Software development
Application: technically new data structure because of latency requirements.
Records: Git commit → Jira ticket → benchmark → failed solution approach → new data structure → new benchmark.
The records do not need to be a polished final report. They must show what was done technically and how the development actually progressed — including the approaches that did not work.
What happens if the WBSO records are not in order?
During an RVO audit, inadequate records may lead to hours, costs or even entire projects not being accepted. RVO may then issue a corrective S&O-verklaring and adjust payroll tax reductions previously granted. For self-employed professionals, the S&O-verklaring may be withdrawn. A fine may also be imposed.
Are your records RVO-proof?
Work through these six questions. If the answer to any question is “no”, there is an administrative risk in an audit.
- 01 Can I see per person and per day how many R&D hours were worked?
- 02 Can I show per project what was technically developed or investigated?
- 03 Can I demonstrate technical progress with dated documents?
- 04 Can I explain why the hours correspond with the project records?
- 05 Can actual costs be evidenced by both invoice and payment?
- 06 Does everything correspond with the S&O-verklaring and the final statement of realisation?
From administration to realisation and audit
Reporting realisation
Report the R&D hours realised and, where applicable, actual costs and expenditures after the end of the calendar year.
RVO audit
RVO may request and assess your records.
Additional questions
Have you received questions from RVO about your application or records? A sound substantiation is decisive.
Frequently asked questions about WBSO administration
Which records are mandatory for WBSO?
Project records and hours registration are always mandatory. If you opted for actual costs and expenditures, records of costs and expenditures are also required.
How quickly must the hours registration be updated?
Within ten working days. The registration must also correspond with holiday and sickness records.
How often must the project records be updated?
No later than two months after the end of each calendar quarter.
How long must I retain WBSO records?
Seven years. Make sure digital documents, version history and tickets remain traceable after system migrations as well.
Do I need to retain failed solution approaches?
Yes. This documentation in particular helps show that there was technical uncertainty and in-house development work.
Do I need cost records if I use the fixed amount?
No. If you chose the hourly costs-and-expenditures allowance, separate records of costs and expenditures for WBSO are not required.
What happens if the records are incomplete?
RVO may reject hours, costs or projects, issue a corrective S&O-verklaring and, in certain cases, impose a fine.
From when does the record-keeping obligation apply?
For employers, from the start month of the application; for self-employed professionals, from the start date of the application.
Are your WBSO records RVO-proof?
We review your hours registration, project records and cost records before a statement of realisation or RVO audit.
Have my WBSO records reviewed Prepare for an RVO audit
SOURCES AND SUBSTANTIVE REVIEW
RVO — WBSO Guide 2026
Reviewed by Peter Klaren, WBSO specialist since 2004. Last substantively updated: 21 September 2026.