The calculation of working hours is based on a simple arithmetic formula, but its practical implementation raises questions that the formula alone does not resolve. Between breaks whose legal status varies according to collective agreements, travel times sometimes reclassified as effective working time, and tracking tools that collect more data than they should, the subject goes far beyond the subtraction of an arrival time from a departure time.
Monitoring Working Time and Limits Set by the CNIL
Even before choosing a calculation tool, a legal constraint frames what the employer can collect. Software that deduces activity from keyboard or mouse movements does not provide a reliable count. In a decision from December 19, 2024, the CNIL fined a company 40,000 euros for using a device that measured supposed periods of inactivity and took screenshots.
The CNIL reminds us that a meeting, a phone call, or any task without interaction with the computer still counts as effective working time. This type of software, presented as a productivity tool, can backfire on the employer in the event of an audit.
The principle of data minimization from the GDPR also applies to tracking hours. Several sanctions imposed in 2025 concerned video surveillance and the permanent geolocation of professional vehicles. Monitoring working time does not justify continuous collection when less intrusive means exist. A self-declared time tracking validated by the manager, for example, is sufficient in most cases.
To delve deeper into calculation methods on Make It Now, several approaches are detailed according to the type of contract and the size of the company.
Calculating Working Hours: What the Basic Formula Doesn’t Say
The classic formula (departure time minus arrival time minus break) works for an isolated day. Difficulties arise as soon as we move to a monthly or annual scale.
Part-Time Work and Additional Hours
A part-time employee whose contract stipulates 24 hours per week can perform additional hours. These are subject to a ceiling and a different increase than full-time overtime. Confusing the two regimes skews the payroll calculation and exposes the company to an adjustment.
Annualization and Modulation
Some collective agreements allow for the distribution of working hours over the year rather than the week. The weekly count then loses its meaning: an employee can work 42 hours one week and 28 the next without triggering an increase, provided that the annual total respects the threshold set by the agreement. Without rigorous cumulative tracking, discrepancies go unnoticed until the end-of-period balance.
Breaks and Travel Time
The lunch break is not considered effective working time if the employee can freely engage in personal activities. However, a mandated break in a specific location, with no possibility of leaving the premises, may be reclassified. Field reports vary on this point depending on the sectors: in catering or logistics, the boundary between actual breaks and permanent availability remains blurred.
Self-Declared Time Tracking, Timesheets, or Management Software
Companies have three main categories of tools to track hours, each with specific limitations.
- The paper timesheet or spreadsheet is still used in small structures. Their cost is zero, but they rely entirely on the declarative rigor of the employee and the manager. Data entry errors and omissions accumulate over the weeks.
- The automated time tracking software (badge, mobile app, terminal) reduces human errors. It generates usable data for payroll and HR dashboards but requires defining the counting rules in advance (rounding to the quarter hour, automatic deduction of breaks, management of anomalies).
- The time management software integrated into an HRIS centralizes time tracking, scheduling, absences, and payroll in one system. Reliability increases, provided that the configuration accurately reflects the applicable collective agreement and company agreements.
The choice depends on the workforce, team mobility, and budget. A well-maintained spreadsheet may suffice for a structure of five people. Beyond twenty employees, manual management consumes disproportionate time.
Remote Work and Hour Calculation: A Still Unclear Framework
Remote work complicates tracking because it removes the physical point of clocking in. An employee working remotely remains subject to the legal or contractual duration, but the employer cannot impose a system of permanent surveillance to check their presence in front of the screen.
Several solutions exist without falling into excessive surveillance:
- A declarative system where the employee records their start and end times via a simple application.
- Task and deliverable tracking rather than hourly tracking, suitable for autonomous positions and day packages.
- Fixed availability time slots, combined with flexibility for the rest of the day, allowing reasonable control without intrusion.
The available data do not allow us to conclude that a single method works for all sectors. Production, customer support, or software development jobs do not have the same constraints for synchronous availability.
The calculation of working hours remains a topic where the technique (the formula, the tool) represents only a fraction of the problem. Regulatory compliance, respect for the GDPR, and adaptation to the actual working mode of employees weigh more than the choice between a spreadsheet and software. A poorly configured tool produces false data with an appearance of accuracy, which is worse than a manual count acknowledged as approximate.
