AFTER THE APPLICATION · HOURS REGISTRATION

WBSO hours records: which hours do you have to register?

Hours records are a key part of every RVO audit. They must show, per day, which employee spent how many R&D hours on which approved project. Good WBSO hours records do not only show how many hours were booked, but make it plausible per employee, project and day that those hours were actually spent on the approved R&D.

BY PETER KLAREN · LAST CHECKED SEPTEMBER 2026 · SOURCE: WBSO GUIDE 2026

WBSO hours records at a glance

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What must you record?

At minimum, record who, on which day, on which approved R&D project and how many hours spent on qualifying R&D.

WBSO does not require a fully closed hours registration in which every non-R&D minute is accounted for. The WBSO records must above all make sufficiently clear and verifiable how many R&D hours were actually realised.

A short description of the technical activity per line is not formally required, but considerably strengthens the connection with the project records in an audit.

When do you have to register WBSO hours? The 10-working-day rule

It is therefore not sufficient to reconstruct a timesheet afterwards at the end of the quarter or the year. A timesheet drawn up afterwards does not meet this requirement, even if the numbers are correct.

Note the difference in deadlines: the period of two months after the end of each calendar quarter applies to the project records, not to the hours records.

Example WBSO timesheet

RVO does not prescribe a specific software package or format. You may use your existing time registration system, as long as it is clear per person, project and day how many qualifying R&D hours were made.

This is a tool from Klaren Subsidieadvies and not an official RVO document.

Which hours do and do not count?

May hours of freelancers, interns and external developers count?

For employers, only R&D hours of employees who are employed by the company applying WBSO can be declared as R&D hours. Hours of interns, graduation students and external freelancers therefore do not count as own R&D wage hours.

This does not automatically mean that all external work is irrelevant: some external activities can, under conditions, be treated as costs or expenditures. For that, read WBSO costs and expenditures.

WBSO hours records for self-employed professionals

For self-employed professionals, correct registration of their own R&D hours is extra important, because a minimum of 500 R&D hours per calendar year are required for the R&D deduction. In addition, the general fiscal hours criterion of 1,225 hours.

applies for the entrepreneur's allowance. So do not only register the total, but here too per day and per project. See the other WBSO requirements for self-employed professionals.

Hours records and project records must tell the same story

Suppose the timesheet says: employee X — 120 hours — project “Sensor development”. Then the project records must also show which technical activities were carried out during that same period.

The three WBSO records must connect to each other. Hours without technical substantiation and technical documentation without accompanying hours are both a risk in an audit.

View the complete overview of WBSO records →

Common mistakes in WBSO hours records

1. 01reconstructing hours months later;
2. 02registering only monthly totals instead of daily records;
3. 03not recording a project number or project link;
4. 04including non-R&D activities in the R&D hours;
5. 05declaring external hours as own employee hours;
6. 06booking hours outside the approved project activities;
7. 07discrepancies with sickness and leave records;
8. 08hours records and technical project documentation telling different stories.

What does RVO check in the hours records?

In an audit, RVO can, among other things, verify:

• which persons worked on the project;
• how many R&D hours were registered daily;
• whether the employees were employed by the applicant company;
• whether the activities were qualifying R&D;
• whether the registration connects with the project records;
• whether the registration connects with sickness and leave data.

Read how a WBSO audit by RVO proceeds →

How long do you have to keep the hours records?

The complete R&D records — including the hours registration — must be 7 years kept. Ensure that hours registrations remain exportable and traceable to person, project and date after a system change.

Hours must be traceable to the approved R&D project. Under conditions, non-realised hours may be shifted within the same calendar year between already approved projects.

Frequently asked questions about WBSO hours records

SOURCES AND SUBSTANTIVE REVIEW

RVO — WBSO Guide 2026

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