You’ve probably thought it many times: “We should do something with the mobility budget.” But once you get started, you realize it’s not as simple as it seems. What’s allowed? What isn’t? How do you calculate the amount?
How do you translate that into a clear policy that’s both legally compliant and practical for your employees?
Colleague Bert Van Molle, Sales & Marketing Manager at Olympus Mobility, answers some of your most frequently asked questions about the mobility budget and how to implement it. This way, you’ll be ready for a federal, legally compliant mobility budget policy that truly works in practice.
Contents:
- What is the mobility budget and why does it exist?
- How does the mobility budget work in practice, and what exactly are the “three pillars”?
- How do you get started as an employer?
- How do you create a clear policy?
- What about taxation and social contributions?
- How do you manage the mobility budget without drowning in Excel?
- What are common mistakes (and how can you avoid them)?
- Finally: Is the mobility budget mandatory?
- And how can Olympus Mobility help?
1. What is the mobility budget and why does it exist?
The mobility budget is an alternative to a company car in Belgium.
Instead of receiving a company car, an employee can opt for a budget that can be used for other, more sustainable forms of transportation — such as cycling, public transport, or shared mobility — or even for housing costs, like rent or a mortgage near the workplace.
If there’s any budget left at the end of the year, it can be paid out as a one-time cash amount directly into the employee’s bank account.
The goal of the mobility budget is to encourage companies and employees to make more conscious mobility choices. The system promotes sustainable modes of transport such as cycling, train travel, or shared mobility, while giving employees more freedom to tailor their commuting to their own situation. At the same time, the tax benefits of a company car are largely preserved, making the mobility budget a financially attractive solution for both employers and employees.
2. How does the mobility budget work in practice — and what exactly are the “three pillars”?
At its core, the system is simple: the mobility budget replaces the company car with a single annual amount that the employee can freely spend on sustainable alternatives.
This amount isn’t just “extra salary” — it’s a conversion of the total cost of ownership (TCO) of the car the employer would normally provide (including lease, fuel, maintenance, insurance, and so on).
Once the budget is determined, it is divided into three legally defined pillars. These pillars determine how employees are allowed to use their budget.
In practice:
- You calculate the budget per employee based on the reference car. This can be done using two TCO-based formulas:
- either based on the average annual cost of the car,
- or through a fixed amount per car type, supplemented by a variable component.
- You define the rules in a clear policy and add it as an annex to the employment contract.
- You make the budget available to the employee through a mobility platform (such as Olympus Mobility), where all expenses are automatically tracked.
- The employee chooses how to spend the budget within the framework of the three pillars.
- You monitor everything via reporting, either manually or through the digital platform.
Pillar 1: Environmentally friendly company car
You allow an environmentally friendly company car in exchange for the budget. In practice, this increasingly means zero-emission vehicles. In your policy, you define the type of car allowed, how charging and parking work, and how you monitor the TCO of such a vehicle.
Pillar 2: Sustainable mobility and housing costs
This is the core of “sustainable mobility.” Think of public transport, bicycle leasing, shared cars, taxis, parking, renting, or charging.
Employees can also include housing costs if they live close to their workplace (typically within a 10 km radius). Companies often set clear limits and rules here — defining what qualifies, where it applies, and how employees must prove a mortgage or rental agreement.
Pillar 3: Cash balance
Is there money left at the end of the year? Then the remaining amount can be paid out to the employee’s bank account, subject to a special employee contribution of 38.07%.
Smart policies encourage employees to use their budget primarily within Pillars 1 and 2, keeping Pillar 3 limited.
3. How do you get started as an employer?
Who is eligible?
- Employer: You offer company cars, or your car policy grants a right to one.
- Employee: The employee has a company car or the right to one. Make sure this is clearly stated in your policy. Avoid exception rules that could lead to confusion or disputes later on.
What should you arrange administratively?
Four key elements:
- A policy with clear rules,
- An annex to the employment contract,
- A digital system to manage budgets and reporting via a mobility platform,
- Internal communication with a clear Q&A for employees.
How do you start in practice?
Once your policy is ready, you can test the mobility budget system with a pilot project. This step isn’t mandatory, but it can be valuable for larger organizations.
- Choose one specific target group — for example, employees with outdated cars — and test the system for a few months using your mobility platform.
- This way, you’ll quickly learn what works well in practice and what needs fine-tuning before rolling it out company-wide.
More about the mobility budget
The federal mobility budget in 2026: Get ready
How does the federal mobility budget work?
How do I calculate the Total Cost of Ownership (TCO) for the mobility budget?
4. How do you create a clear policy?
Step 1: Define your goal
Why are you introducing a mobility budget? Try to express it in one clear sentence. It may sound simple, but it changes everything.
- Do you mainly want to control costs? Then focus on TCO (Total Cost of Ownership) and tight management.
- Do you want to reduce CO₂ emissions? Then emphasize sustainable modes of transport within your pillars.
- Do you want to increase employee satisfaction? Then give employees as much freedom of choice as possible.
Once you know why you’re implementing it, it becomes much easier to make decisions about budget, transport options, and communication. Your goal becomes the guiding filter for every decision that follows.
Because the mobility budget isn’t just a financial benefit — it’s a functional system that requires clear agreements. A well-written policy ensures everyone understands who is entitled to what, how much, and under which conditions. It helps you avoid confusion, endless questions, and fiscal misunderstandings later on.
Step 2: Determine the budget — how to calculate the mobility budget
How do you determine the amount per employee? There are two TCO-based formulas, both using a reference car:
- TCO based on the average annual cost of the reference car
Start from the total annual cost, including: lease/financing, energy or fuel, insurance, maintenance, taxes, non-deductible VAT, and any company car benefit (VAA) impact. - Flat-rate TCO per car class/type with a variable component
Apply a fixed TCO component per car class and add a variable element (for example, a kilometer or energy component).
Review your car policy and HR context to determine which method fits best. Apply your choice consistently per job category, and record it clearly in your policy.
Also specify when and how the amount will be reviewed — for example, annually or when an employee’s role changes.
Step 3: Decide which transport options to include
What do you allow in Pillar 2? This is the most strategic step — it’s where you shape your company’s vision on mobility. Be specific. Literally list in your policy:
- Which transport modes are allowed (NMBS, De Lijn, TEC, MIVB, bike leasing, shared cars, taxis, parking, charging),
- What limits or caps apply, and
- How employees should register purchases or subscriptions.
Also mention what’s not allowed — for example, parking unrelated to sustainable travel (like private parking without a link to commuting).
Want to know what’s allowed? Read our blog: Parking with the mobility budget.
Step 4: Include housing costs (or not)
A common question: Can rent or a mortgage be included in Pillar 2?
The answer is yes — under specific legal conditions.
Employees can pay their rent or mortgage repayments with their mobility budget if they live within a 10 km radius of their main workplace.
Employees who work from home more than 50% of the time also have the right to use their mobility budget for rent or loan payments.
All payments must, of course, be properly documented. With Olympus Mobility, this happens automatically: the platform verifies whether certificates and proof documents meet legal requirements, ensuring full fiscal compliance.
Step 5: Translate your policy into the employment contract
A clear annex to the employment contract is mandatory.
This should include:
- The eligibility criteria,
- The minimum duration (at least 12 months),
- The calculation method,
- The eligible expenses per pillar,
- The control and reporting process, and
- What happens in case of termination, suspension, or misuse (e.g. resignation, illness, or role change).
Write it in legally accurate yet understandable language — avoid jargon. The annex is a contract, but also a communication tool. Every employee should be able to read and fully understand it.
Step 6: Communicate, communicate, communicate
How do you engage employees in the story? By making it tangible.
A policy is just paper — a mobility budget only comes alive when people understand how to use it.
Follow these three simple steps:
- Explain: Give a short presentation or Q&A session explaining what the mobility budget is, why it’s beneficial, and what will change. Olympus Mobility can support you with ready-to-use employee communication tools.
- Show examples: “With €6,000 per year, you can pay for your train pass, lease a bike, and occasionally use a shared car.”
- Provide access: In the Olympus app, each employee can see in real time how much budget remains, which pillar they’re using, and what’s allowed. It makes the system visual and easy to understand.
5. What about taxation and social contributions?
How is the mobility budget taxed?
That depends on which pillar the expense falls under. The strength of the federal or legal mobility budget lies precisely in its fiscal logic — sustainable choices are rewarded.
Let’s briefly go through each pillar.
Pillar 1: Environmentally friendly company car
If you still choose a company car within your mobility budget — but one that’s environmentally friendly — it receives the same tax treatment as a regular company car.
The benefit in kind (VAA) still applies, but because of the low CO₂ emissions or electric drive, the taxable benefit is significantly lower.
For the employer, the cost remains deductible as a salary expense, and the car is accounted for within the TCO of the budget.
In short: the more environmentally friendly the car, the greater the tax benefit. From 2026 onwards, this will even become mandatory — all cars within Pillar 1 must be fully electric.
Pillar 2: Sustainable mobility and housing costs
This pillar offers the greatest tax advantages. Everything that falls under Pillar 2 — such as public transport, bicycles, shared mobility, rent, or mortgage payments near the workplace — is exempt from both taxes and social security contributions (RSZ).
Of course, there are specific conditions:
- The expenses must genuinely relate to mobility or housing.
- Housing costs only qualify if the employee lives within a 10 km radius of their main workplace.
- Payments must be properly recorded through a recognized channel, such as the Olympus Mobility platform.
For the employer, these costs are fully tax-deductible, just like regular salary expenses. And because they’re exempt from social security contributions, both the employer and the employee enjoy a net financial benefit.
In short: Pillar 2 is pure fiscal gold. The more employees spend their budget there, the more efficient the entire system becomes.
Pillar 3: Cash balance at the end of the year
If the budget isn’t fully used, the employee can have the remaining amount paid out into their bank account — but this comes with a special employee contribution of 38.07%. This replaces the standard social security contribution and ensures the system remains fair.
For the employer, there is no parafiscal cost in this pillar.
In short: Pillar 3 is the safety net, not the goal.
And for the employer?
From the employer’s perspective, all three pillars are tax-deductible as salary costs. There is no additional corporate tax on the mobility budget itself.
However, it’s essential to ensure that all payments are properly linked to an individual mobility account for each employee, so the payroll provider can process the correct salary line.
The Olympus Mobility platform automates this process: every transaction is automatically assigned to the right pillar and correctly forwarded to payroll.
Are there risks if you don’t follow the rules?
Yes. If you record expenses that don’t fall within the pillars or fail to document them properly, the tax authorities may classify them as regular salary. This can lead to social security and tax adjustments. That’s why a clear policy and a smart platform are essential.
In short
- Pillar 2 = the most tax-efficient (exempt from social security and income tax).
- Pillar 3 = the safety net, not the main goal (38.07% contribution).
- Clear administration = necessary proof for compliance.
- Electric vehicles = the future of Pillar 1 (mandatory from 2026).
6. How do you manage the mobility budget without drowning in Excel?
With the Olympus Mobility platform. There, you can set budgets per job category, activate the allowed mobility options for employees in the Olympus app, and be confident that every expense complies with legal requirements.
This way, you can easily manage each pillar and save a significant amount of time for HR, Fleet, and Payroll teams.
How does it work for employees?
In the Olympus app, employees can choose from over 40 sustainable mobility options — from public transport to shared mobility. They can instantly see their remaining budget and what is allowed under their company’s policy.
Our support team is always ready to help, and thanks to preferential rates with partners such as cambio and Hertz, employees get even more value from their budget.
And what about reporting?
In the Olympus management portal, you get clear dashboards showing how mobility options are used and how budgets are spent. This lets you adjust your mobility policy based on data — not gut feeling.
7. What are common mistakes (and how can you avoid them)?
According to Bert Van Molle, Sales & Marketing Manager at Olympus Mobility, there are four issues that keep coming back. They may seem small, but they cause most of the frustration later — both for HR and employees.
1. Vague rules in Pillar 2
Pillar 2 is fantastic, but also the most complex part of the mobility budget. It covers sustainable mobility and housing costs — but clarity is key.
Some companies simply write: “Bicycles, public transport, and housing are allowed.” Period. The result? Confusion and discussion. Is an e-scooter allowed? What about station parking? Or renting a garage?
Tip: Include concrete examples in your policy. Clearly list what is and is not allowed. For example: “Allowed: NMBS, De Lijn, TEC, MIVB subscriptions, bike leasing via a certified provider, rent or mortgage within 10 km of the workplace.” It may seem overly detailed, but it saves you countless emails later on.
2. No clear policy owner
The mobility budget sits at the crossroads of HR, Fleet, and Finance — and then often, no one really takes the lead. Who decides on exceptions? Who tracks the budget? Who approves purchases? Without a single policy owner, you end up with chaos.
Tip: Assign a clear responsible person, typically someone from Comp & Ben or HR operations with a defined mandate to make decisions. That person ensures the rules are respected, keeps everything legally compliant, and serves as the main point of contact for employees.
3. Forgetting communication
The biggest misconception: “We’ve finished the policy, so everyone knows what to do.” Unfortunately, that’s rarely true. Many employees don’t immediately understand the mobility budget. They think they’re losing something (“My company car is gone”) instead of gaining something (“I get flexibility and choice”).
Our advice: plan three key communication moments:
- Announcement: explain why you’re introducing it — sustainability, freedom, flexibility.
- Launch: show examples of how employees can use their budget.
- Follow-up: after three months, share data and success stories (“We’ve seen a clear rise in train and bike use.”).
Use visuals, FAQs, and short videos. In the Olympus app, employees immediately see what’s possible — that makes it tangible and engaging.
4. Too much Excel
Excel works fine for a test user — but not for 150 employees. As soon as you start processing receipts, housing documents, or shared-mobility trips manually, you’re in for hours of administration and potential errors.
And errors in the mobility budget can lead to tax risks or even sanctions under the social penal code.
Tip: use a platform that automates administration. With Olympus Mobility, you manage budgets, pillars, and supporting documents digitally.
Employees book their mobility directly through the Olympus app, and payroll administration becomes much easier thanks to the automatic link with the social secretariat. For Finance, the monthly invoice remains a convenient summary of all mobility expenses.
8. Finally: Is the mobility budget mandatory?
Is the mobility budget mandatory for employers?
As of 2025, not yet. There is no law requiring companies to offer a mobility budget. You decide whether it fits within your compensation policy or car policy.
However, the political intention is clear. The federal government has announced plans to make it mandatory from January 1, 2026 for employers who offer company cars. The idea: employees should always have the choice between a car or a mobility budget.
And for employees? Are they obliged to switch?
No. It remains voluntary for them as well. An employee entitled to a company car can choose: keep the car or switch to the mobility budget. It’s about freedom of choice, not obligation.
Why should a company start now?
Because waiting rarely pays off. Companies that prepare their mobility budget policy today will be ready for what’s coming:
- Stricter CO₂ standards
- Faster electrification
- More hybrid work
The transition goes much smoother when you gain experience early. You can test, learn, and build your own logic around TCO, pillars, and communication.
Also read: Why now is the moment to implement the mobility budget.
And how can Olympus Mobility help?
Okay, Bert — the mobility budget sounds great, but it also seems like a lot of work. How does Olympus Mobility help with that?
I hear that a lot, and honestly? It can get complicated — if you try to do it manually. Receipts, Excel files, reimbursements, certificates… it’s easy to lose track.
That’s where Olympus Mobility comes in.
Our mission is simple: make the mobility budget practical and manageable — for HR, Finance, and employees alike.
One platform, one overview
With Olympus Mobility, you manage all mobility options — from public transport and bike leasing to shared cars, parking, refueling, and charging — in one platform. Employees use the app to plan their trips, check their remaining budget, and pay automatically. You receive a single digital monthly invoice.
Automatic link with payroll and the social secretariat
All transactions from Pillars 2 and 3 are automatically processed and correctly forwarded to your social secretariat. This keeps your fiscal and social administration fully compliant — even when the remaining balance is paid out.
You don’t need to worry about whether an expense is subject to social security contributions — the Olympus Mobility platform fully adheres to federal mobility legislation.
Transparency for everyone
Every employee can see in real time:
- how much budget is left,
- what is allowed within each pillar, and
- what their CO₂ impact is.
For HR and Comp & Ben, that means fewer questions, less follow-up, and better control over the numbers.
Conclusion
With the mobility budget, you give your people choice, keep your costs under control, and take steps toward lower CO₂ emissions. Start small, define your rules clearly, and automate wherever possible — that way, it won’t become a project, but part of everyday practice.