What is the CO2 solidarity contribution?
The CO2 solidarity contribution (cotisation de solidarité / solidariteitsbijdrage) is a flat monthly social security contribution that a Belgian employer pays to the National Social Security Office (NSSO) for each company car it makes available for private use or for commuting. The benefit the employee gets from the car is excluded from pay for social security purposes, and this contribution takes the place of the normal contributions on it.
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The contribution depends on the car’s CO2 emissions, in grams per kilometre, and its fuel. The legal formulas give a monthly amount before indexation:
- petrol: ((CO2 x 9) minus 768) / 12;
- diesel: ((CO2 x 9) minus 600) / 12;
- LPG or natural gas: ((CO2 x 9) minus 990) / 12.
For 2026 the result is multiplied by 185.85 and divided by 114.08. The contribution is due for every car, whatever the employee pays towards its private use, and even if private use is banned but the car is used to commute.
Higher contribution for cars ordered since July 2023
For cars bought, leased or rented from 1 July 2023, the calculated contribution is multiplied by a coefficient that rises each year: 2.25 from July 2023, 2.75 from 2025, 4.00 from 1 January 2026 and 5.50 from 1 January 2027. The date that counts is the signature of the order form or of the lease or rental contract, so cars ordered before July 2023 keep the original formula.
A minimum applies in every case, and the coefficient is never applied to it. In 2026 the indexed minimum is €42.34 a month for cars ordered after 30 June 2023 and €33.93 for older cars. Electric cars pay the minimum.
A worked example
A petrol car that emits 120 g/km gives ((120 x 9) minus 768) / 12 = €26.00 before indexation, or €42.36 a month in 2026. If the car was ordered before July 2023, that is the contribution. If it was ordered later, the 4.00 coefficient brings it to €169.43 a month.
Declaring and paying it
The employer declares the total in its quarterly social security declaration (DmfA), with the number plate of each car, and reports each employee’s benefit in kind with their pay data. If cars are left out or wrongly declared to avoid the contribution, the NSSO charges a flat penalty of double the contribution.
CO2 contributions when TopSource runs your payroll
When TopSource runs your payroll in Belgium, we work out each car’s monthly contribution from its emissions, fuel and order date, apply the right coefficient and minimum, and declare it with the number plates in the DmfA.
Frequently asked questions
How much is the CO2 solidarity contribution for an electric company car in 2026?
The minimum: €42.34 a month for cars ordered after 30 June 2023 and €33.93 a month for electric cars ordered earlier.
Why is the contribution higher for some company cars?
For cars bought, leased or rented from 1 July 2023, the calculated contribution is multiplied by a coefficient, which is 4.00 in 2026 and rises to 5.50 from 1 January 2027.
Does the employee pay the CO2 solidarity contribution?
No. It is an employer contribution, due for each car whatever the employee pays towards its private use.
Related terms in Belgium
- Joint Committee (Belgium)
- Dimona Declaration (Belgium)
- Unified Status (Belgium)
- Outplacement Obligation (Belgium)
- Non-Compete Clause (Belgium)
- Time Credit (Belgium)
- Work Regulations (Belgium)
- Single Permit (Belgium)
- Ecocheques (Belgium)
- Payroll Withholding Tax (Belgium)
- Automatic Salary Indexation (Belgium)
- Meal Vouchers (Belgium)
- Benefit in Kind for Company Cars (Belgium)
- Group Insurance and the 80% Rule (Belgium)
- Tax Form 281.10 (Belgium)