Introducing flexitime: what to include in your work rules

Employees deciding for themselves whether they start at 7.30 or at 9.00: for office roles, planners, technical services and administrative teams that is now almost a baseline expectation. Since the 2017 Act on Feasible and Manageable Work, this kind of flexitime arrangement also has a clear legal framework in the Belgian Labour Act. That framework is not a formality: without the right provisions in your work rules, you are running an arrangement that will not survive a visit from the labour inspectorate.

Below you will find what flexitime actually is, which elements you are obliged to record, how to amend your work rules, and where things go wrong in practice.

What exactly is a flexitime arrangement?

Under a flexitime schedule, the average working time is fixed, but the exact start and finish time of each day is not. Within agreed margins, the employee chooses when to start, take a break and stop — provided they are present during the mandatory core hours.

A concrete example for a 38-hour week in a manufacturing company:

• Morning flexible band: 07.00 – 09.30 (free choice of start time)
• Core hours: 09.30 – 12.00 (attendance mandatory)
• Flexible lunch break: 12.00 – 14.00, minimum 30 minutes
• Core hours: 14.00 – 16.00 (attendance mandatory)
• Evening flexible band: 16.00 – 18.30 (free choice of finish time)

An employee who starts at 07.00 and leaves at 15.30 works 8 hours. Someone who starts at 09.00 and stops at 18.00 works 8.5 hours. Over the reference period, the average has to come out at the contractual working time.

An important distinction: flexitime is not a variable work schedule. With variable part-time schedules, the employer sets the hours and you have to publish them in advance — as we described in publishing variable part-time schedules in the care sector. With flexitime, the employee chooses within a fixed framework.

Mandatory: everything in the work rules (or a CLA)

A flexitime arrangement must be laid down in the work rules, or in a collective labour agreement that you incorporate into the work rules. An email to the team or an arrangement agreed per department is not enough.

These elements belong in there as a minimum:

1. The average weekly working time that has to be respected (e.g. 38 hours, or the part-time equivalent).
2. The reference period over which that average is measured.
3. The core hours: the periods during which attendance is mandatory.
4. The flexible bands: the margins within which the employee decides on start, finish and break.
5. The daily and weekly maximum limits that apply within the arrangement.
6. The carry-over rules for a surplus or shortfall moving into the next reference period.
7. The time-tracking system you use and how the employee can consult their balance.
8. Who the arrangement applies to: which roles, departments or sites.

Also add practical provisions that prevent arguments later: what happens with a team meeting outside core hours, what happens at shift handover, who may approve an exception, and how you deal with business travel.

The limits you may not exceed

Within a flexitime arrangement, stricter daily and weekly ceilings apply than under classic working-time flexibility:

• A maximum of 9 hours per day
• A maximum of 45 hours per week

On top of that, the usual rules remain in force: at least 11 consecutive hours of rest between two working periods, and a break of at least fifteen minutes as soon as the working day exceeds six hours. So someone who works through until 18.30 cannot start at 05.00 the next day — not even "voluntarily".

At the end of the reference period, the balance must in principle be back at zero. The law allows a maximum of 12 hours of surplus or shortfall to be carried over to the next period. Hours above that ceiling do not in principle give rise to additional pay — unless they were worked at the employer's request, because then they are genuine overtime, with the corresponding premiums and compensatory rest. A structural shortfall can be deducted.

That 12-hour ceiling is precisely why a flexitime system without proper monitoring is risky: if someone suddenly shows a 40-hour surplus in March, you have a problem you can no longer solve neatly. Also read is your staff working the hours planned, or far too much overtime? for the wider logic around balance monitoring.

The reference period: a quarter or longer?

By default, the average is measured per quarter. Through a CLA or through the work rules, that period can be extended up to a maximum of one year. Always check your sectoral CLA first: in some sectors the reference period has already been set collectively and you have no freedom of choice.

Practical advice: only choose a longer reference period if you also have the discipline to follow up monthly. An annual reference period sounds comfortable, but it makes it easier to discover only in November that half your teams have worked too much or too little. A quarter forces a conversation four times a year — often healthier.

Time tracking is not optional

Anyone introducing flexitime schedules must have a reliable time-tracking system. That system records, per employee, when the working day starts and ends, and the breaks in between. Employees must be able to consult their own data and balance, and the data must be available to the labour inspectorate.

In practice this means: no paper list on the wall and no spreadsheet that someone fills in afterwards from memory. With digital time tracking, your hours worked, your balances and your payroll processing all come out of the same system. When registration and planning are linked, you immediately see the difference between what was planned and what was actually worked — the basis for keeping the 12-hour ceiling under control.

How to amend your work rules correctly

Amending the work rules follows a set procedure:

• With a works council: the amendment is discussed and approved in the works council, in line with the procedure that applies there.
• Without a works council: you post the draft in a clearly visible place and give every employee the opportunity to record comments in a register for 15 days. If no comments are made, the amended rules take effect. If comments are made and no agreement is reached, the labour inspectorate or a social conciliator becomes involved.

Afterwards, send a copy of the amended rules to the competent Supervision of Social Legislation office (within the statutory deadline of eight days after entry into force) and make sure every employee receives or can consult a copy. If you operate several sites, keep track of which version applies where — that is exactly the kind of document management you are best off keeping centrally in your HR administration.

Which sectors does flexitime work for (and where not)?

Flexitime works best where output is not tied to fixed opening or production hours:

• Industry and manufacturing: ideal for engineering, planning, quality, purchasing and administration. On the line itself, shift work remains the rule.
• Logistics and transport: usable for dispatch support and administration, far less so for loading docks with fixed slots.
• Care: feasible for support services, not for care teams that need continuity at the bedside.
• Retail and hospitality: opening hours determine staffing levels, so flexitime is rarely workable on the floor here — in the office it is.

A mixed approach is perfectly possible: flexitime for office roles, fixed or variable schedules for the operational teams. In that case, state clearly in the work rules which staff category falls under which arrangement.

Five pitfalls

1. Not defining core hours. Without mandatory core hours, team meetings disappear and you end up arguing about availability.
2. Making core hours too wide. 8.30 to 17.00 as core hours is not flexitime, it is a fixed schedule with a different label.
3. Only looking at balances at the end. The 12-hour ceiling leaves no room for a last-minute catch-up.
4. Confusing flexitime with overtime on request. Hours you ask for are overtime, with a premium. Make that distinction visible in your approval flow.
5. Forgetting to check the sectoral CLA. Some sectors limit the reference period or impose additional conditions.

Checklist for your roll-out

• Sectoral CLA checked for existing agreements on working time and reference periods
• Core hours and flexible bands set per job group and tested with the managers involved
• Reference period chosen and a monthly follow-up moment scheduled
• Carry-over rules (max. 12 hours) and the consequences of a surplus or shortfall written out
• Time-tracking system operational, with access for the employee
• Work rules amended via the correct procedure and sent to Supervision of Social Legislation
• Clear communication to your staff: what is allowed, what is not, and who approves what

Flexitime schedules are one of the cheapest ways to offer flexibility without disrupting your organisation. But they stand or fall on two things: work rules that are correct, and time records you can rely on every single month.