TCO guide for HR: calculate the mobility budget in 5 steps

The federal mobility budget is becoming mandatory: from 1 January 2027 for companies with more than 50 employees, and from 1 January 2028 for companies with more than 15. For some 40,000 Belgian businesses, it all starts with one question: how much budget does an employee actually get? The answer lies in the Total Cost of Ownership (TCO) of the company car. That might sound like a job for a tax specialist. But with the right information, you'll soon get the hang of it too.

In this guide, you'll learn how to calculate the mobility budget in five steps, from cost list to policy. No double counting, and no spreadsheet taking on a life of its own.

In a nutshell

• The mobility budget is the annual Total Cost of Ownership (TCO) of the company car an employee is entitled to, or hands back.
• For the mobility budget, you use TCO 2: the total annual gross cost of the car to the employer.
• You choose between two legal formulas: the actual cost formula (average of the last four years) or the flat-rate formula.
• You record your choice in your mobility policy, and it applies for at least three years.
• In 2026, the budget ranges from a minimum of €3,233 to a maximum of €17,244 per year.

What is the TCO of the mobility budget?

The Total Cost of Ownership (TCO) is the total annual gross cost of a company car to the employer. It forms the basis for the amount of the mobility budget. If an employee hands back their company car, or is entitled to one, they receive that TCO as a budget for flexible mobility.

The tricky part: not everyone means the same thing by "TCO". There's no legal definition, but the mobility world talks about three levels.

Received a TCO calculation from your leasing company? Check which level it is first. TCO 3 is not the standard for the mobility budget.

• TCO 1: the basic calculation. Direct expenses only: lease or rental price, energy or fuel, CO₂ contribution and non-recoverable VAT. Handy for a simple cost comparison between cars.
• TCO 2: the extended calculation. TCO 1, plus tax and functional costs: taxes, disallowed expenses, the benefit in kind for private use, and insurance. This is the TCO you use for the mobility budget.
• TCO 3: the commercial TCO. TCO 2, plus avoided costs and tax benefits, such as tax savings on leasing costs. Leasing and finance companies use this calculation to compare their offers. It's not the standard for the mobility budget.

Calculating the mobility budget: the step-by-step plan

1. Map out the total annual gross cost of the car (TCO 2).
2. Choose your formula: actual costs or flat-rate values.
3. Choose your calculation basis: individual car, reference car or job category.
4. Avoid double counting and decide on extras.
5. Record everything in your mobility policy and plan the follow-up.

Step 1: Map out the total gross cost of the company car

TCO 2 is the sum of all the costs the car incurs for you as an employer. But watch out: the law contains an exhaustive list. You may only include costs that appear on that list and that your car policy places with the employer.

Tip: gather these costs per car and per job category. That way, in step 3, you can calculate the mobility budget under different scenarios and compare them side by side.

Car

• Lease or rental price
• For purchases or financial leasing: annual depreciation of 20% of the cost price (incl. invoiced options, accessories and discounts)
• Interest on borrowed capital

Energy

• Fuel and electricity costs
• Administration fees for fuel and charging cards

Charging point

• Annual depreciation of 20% of the installation costs, including maintenance and repairs
• Management fees for the charging point and cable

Use

• Tolls, car wash, garage and parking
• Replacement car
• Getting the car road-ready
• Replacing, changing and storing tyres
• Technical inspection
• Service management fees

End of contract

• Assessment fees when the car is returned or changes driver
• Repair costs recorded during the end-of-contract inspection

Insurance and tax

• Insurance
• Employer CO₂ solidarity contribution (NSSO)
• Registration tax and annual road tax
• Non-recoverable VAT
• Tax on the non-deductible portion of these costs
• Tax on the portion of the benefit in kind that counts as a disallowed expense

Step 2: Choose your formula: actual costs or flat-rate values

To calculate the mobility budget, the law gives you two formulas. You can use either, whether you buy or lease your cars.

Formula 1: the actual cost formula. You take the average actual annual cost of the company car over the past four years. That gives you a detailed result, but it also means you need to be able to back up every cost item from step 1. The downside: because it's an average, this formula doesn't account for cost increases during that period. So the result never fully covers the current TCO.

Formula 2: the flat-rate formula. Quicker, because you work with fixed values. The formula differs depending on whether you lease or own the car. If you opt for the flat-rate formula, you must state this explicitly in your policy. That also applies if you decide to stick with it after three years.

For rented or leased cars

Fixed component = the sum of:

• the annual rental or lease cost
• the average annual cost of everything not covered by the contract, over the last three years (provided it's included in the car policy)
• the non-deductible VAT
• the tax on non-deductible car costs
• the employer CO₂ solidarity contribution

Variable component = (6,000 + home-to-work distance × 2 × 200) × consumption cost per kilometre. This only applies if fuel isn't included in the lease price.

For owned cars or cars under financial leasing

Fixed component = list price (as used for the benefit in kind) × 25% + employer CO₂ solidarity contribution

Variable component = (6,000 + home-to-work distance × 2 × 200) × consumption cost per kilometre

How to read the variable component

If an employee lives 20 km from work, you calculate with 6,000 + (20 × 2 × 200) = 14,000 kilometres per year. You then multiply that figure by the car's consumption cost per kilometre.

Step 3: Choose your calculation basis

The formula is the "how". The calculation basis is the "what". You decide whether to apply the formula to:

1. The individual car. The budget is the TCO of the car this employee hands back. Suits companies focused on cost control.
2. A reference car. The budget is the TCO of a set standard car. Suits a simple policy that's easy to explain.
3. The average of the cars (on the road) in a job category. The budget is the average TCO of the cars driven by colleagues in the same role. Suits equal budgets for equal roles.
4. The average of the reference cars in a job category. The budget is the average TCO of the reference cars linked to a role. Suits a generous, predictable budget, in line with your car policy.

Every combination of formula and basis produces a different amount. So run at least two scenarios before you decide.

Step 4: Avoid double counting and decide on extras

This is where things most often go wrong. Run through this checklist before you communicate an amount:

• Lease contract checked. Cost items already included in the lease price (maintenance, tyres, insurance, sometimes fuel) shouldn't be counted again separately.
• Mileage allowance decided. Do you include mileage allowances and other business travel costs in the TCO? Then your employee is no longer entitled to an additional tax-free mileage allowance. If you don't include them, you reimburse them on top of the mobility budget.
• Employee contribution deducted. Does the employee pay a personal contribution towards their company car? Then that amount is deducted from the mobility budget.
• Minimum and maximum checked. The budget must fall within the legal limits. In 2026, these are €3,233 and €17,244 per year. These amounts are indexed annually.

Step 5: Record everything in your mobility policy and plan the follow-up

You're required to state in your mobility policy which formula you use. While you're at it, also record the calculation basis, your choices from step 4 and the follow-up.

Three rules to remember:

• Fixed for three years. Once chosen, you apply the same formula for three years.
• A switch applies to new joiners. If you choose a different formula after three years, you use it for every employee who joins the mobility budget from then on.
• Plan an annual review. How will you map the costs, and who'll keep track of them? Sort this out from the start, and your TCO calculation won't turn into a brand-new spreadsheet project every year.

Which formula suits your company?

There's no "right" formula. But there is one that fits your strategy.

Focused on cost control? Then the actual cost formula based on the individual car is your best fit. Keen to offer your employees an attractive benefit and position yourself as a strong employer? Then the flat-rate formula is the better choice.

Going for the flat-rate formula with reference cars per job category, in line with your car policy? Then you get a generous calculation that, among other things, takes into account fuel costs for employees who regularly work from home.

Actual cost formula

• Basis: average actual annual cost over the last 4 years
• Pro: accurate, close to the real cost
• Con: labour-intensive and doesn't keep pace with rising costs
• Suits: a focus on cost control

Flat-rate formula

• Basis: a fixed and a variable component based on flat rates
• Pro: fast, predictable and a more generous budget
• Con: less closely aligned with the actual cost
• Suits: a focus on employer branding and employees

Ask yourself these questions before you choose:

• Do you want the mobility budget to grow with rising costs?
• Or do you want the TCO to stay the same, or even come out lower?
• Do you want to settle the car costs in the mobility budget individually each year?
• Do you want to combine the mobility budget with existing allowances? If so, which ones, and will you include them in the TCO?
• How do you want to map and monitor costs each year?

Review your answers alongside your existing policies on cars, bikes, public transport and working from home. That way, your TCO method fits seamlessly with your company.

Frequently asked questions about calculating the mobility budget

How do you calculate the mobility budget?

You calculate the mobility budget based on the Total Cost of Ownership (TCO 2) of the company car: the total annual gross cost to the employer. To do so, you use either the actual cost formula or the flat-rate formula.

What's the difference between the actual cost formula and the flat-rate formula?

The actual cost formula takes the average actual annual cost over the last four years. The flat-rate formula works with fixed values, such as 25% of the list price for owned cars, plus a variable component for fuel.

Which TCO do you use for the mobility budget?

TCO 2, the extended calculation. As well as direct costs, it includes taxes, insurance, disallowed expenses and the benefit in kind. TCO 3 is a commercial calculation used by leasing companies and isn't the standard for the mobility budget.

How long do you have to use the same formula?

Three years. After that, you can switch; the new formula then applies to every employee who joins from that point on.

What are the minimum and maximum amounts of the mobility budget in 2026?

In 2026, the mobility budget is at least €3,233 and at most €17,244 per year. The limits are indexed annually.

Do mileage allowances count towards the TCO?

That's your call as the employer. If you include them, the additional tax-free mileage allowance no longer applies. If you don't, you reimburse them on top of the mobility budget.

When does the mobility budget become mandatory?

From 1 January 2027 for companies with more than 50 employees, and from 1 January 2028 for companies with more than 15 employees.

Calculating the mobility budget needn't be a headache

The TCO is the foundation of your mobility budget. Lay it well, and you'll build a policy that adds up, is easy to explain and lasts three years. And after that? Then above all, you'll want your employees to get around worry-free, without you having to chase tickets, refunds and spreadsheets.

That's where we come in. The experts at Olympus Mobility and MBE Mobility Budget Experts help you think through policy choices and TCO calculations. Olympus Mobility is the market leader in mobility budget management and makes day-to-day use simple, for HR and for your employees.

Last updated: September 2026. Sources: Mobility guide "Calculate the TCO" (Olympus Mobility and MBE Mobility Budget Experts); 2026 limits according to HR Alert; official information at mobiliteitsbudget.be.