An on-call worker receives less pay at the end of the month than expected. A freelancer sends an invoice and gets pushback from the client: "That didn't take that long, did it?" An interim manager cannot afterwards demonstrate how many hours he spent on which project.
In each case the cause is the same: no reliable time records. For flexible workers — a broad term covering freelancers, on-call workers, interim professionals, and hybrid workers — logged hours are not a formality. They are the foundation of your income, your tax return, and your professional reputation.
What do we mean by flexible workers?
Flexible workers are everyone who works outside a permanent full-time contract. This includes:
- Freelancers and self-employed: independents who invoice by the hour or by project
- On-call and zero-hours workers: employees whose working hours vary each week
- Interim professionals: temporary workers who work across multiple clients
- Hybrid workers: employees who combine employment with freelance assignments
All these groups share one thing: their worked hours are not automatically recorded administratively. That makes time tracking even more important for them than for permanent employees.
1. Your income stands or falls with what you register
If you work by the hour, every unregistered session is a lost invoice line. That sounds simple, but in practice hours regularly slip through: a short call with a client, a half day split in two, an evening you spent "quickly" fixing something.
Imagine you forget to log an average of half an hour per day. Over a working month of twenty days that is ten hours. At a rate of sixty euros per hour, that is six hundred euros per month you do not invoice — not because you did not earn it, but because you did not record it.
Consistent registration in a tool like PrikKlokPlus prevents this: you link every hour directly to a project and client, so nothing falls through the cracks.
2. The hours criterion: your tax deduction is at stake
For freelancers who want to claim the self-employment deduction, the hours criterion applies: you must spend at least 1,225 hours per calendar year on your business. That amounts to approximately 28 hours per week if you work 45 weeks a year.
Importantly: not only billable hours count. Time spent on administration, acquisition, professional training, consultations with your accountant, and professional networking all count — provided you can demonstrate it.
If you fall short of the threshold, you lose the self-employment deduction entirely for that year. There is no partial credit. The Dutch Tax Authority can request a detailed hours record during an audit, supported by calendar appointments, invoices, and email correspondence. Without reliable records, providing that evidence is nearly impossible.
Exceptions: a reduced threshold of 800 hours applies in cases of disability. For pregnancy, the 16 weeks of maternity leave count toward the calculation.
3. Preventing disputes with transparent timesheets
A client who disputes how many hours you worked is unpleasant. Without documentation you stand on weak ground. With a detailed timesheet per project — including date, time, description, and duration — you have objective evidence that is hard to refute.
This is not only useful in conflicts. Transparent timesheets also increase your credibility as a professional. Clients who can see exactly what you did and how long it took trust you more readily and ask fewer questions about your invoice.
4. Better quotes based on actual time spent
Many flexible workers underprice their work because they do not know how long tasks actually take. A website audit you quote as "a day" that actually takes two — you only know this if you have been tracking it.
After three months of consistent tracking you will see patterns you did not have before. Which clients demand relatively more of your time outside billable hours? Which tasks do you systematically underestimate? Those insights make your next quote more realistic and more profitable.
5. For employers of on-call workers: a legal responsibility
Employers who work with on-call or zero-hours workers are required under the Working Time Act to maintain a reliable record of the working and rest times of their flexible employees. This also applies to staffing agencies and other parties deploying temporary staff.
A digital tool that lets employees enter their own hours — with a manager approving them — makes this administration straightforward and auditable. PrikKlokPlus offers exactly this workflow: employees submit hours, you approve with one click, and the system maintains a complete audit trail.
How to start today
- Choose a tool you will actually use — simplicity beats feature richness when it comes to daily habits
- Create a project for each client or assignment — even if you only have one
- Log immediately after each session — not at the end of the day
- Export a monthly overview — save this in your admin folder as a back-up
Start free with PrikKlokPlus — also for on-call workers and flex teams
Frequently asked questions
Am I required to track my hours as an on-call worker?
The primary responsibility for time registration lies with your employer. Under the Working Time Act, employers are required to record the working hours of flexible employees. As an on-call worker it is nonetheless wise to keep your own records as a check — discrepancies occur and are easier to resolve with your own evidence. Consult a legal adviser if in doubt.
Do non-billable hours count towards the hours criterion?
Yes. For the hours criterion, all hours spent on your business count: acquisition, administration, training, and networking all qualify. You do not only need to log billable hours. Do describe the nature of the work so you can substantiate it if the Tax Authority asks.
What happens if I do not meet the hours criterion?
You lose the right to the self-employment deduction entirely for that year — there is no partial deduction. The same criterion applies when claiming the starter deduction. The SME profit exemption does not lapse if you fall short. Seek advice from an accountant or tax adviser for your specific situation.