Mileage allowance: quarterly indexation returns from 1 July 2026

As of 1 July 2026, the temporary system of monthly indexation of the mileage allowance comes to an end. Employers will once again apply the standard quarterly indexation system where this mechanism is applicable.

This change concerns employees who use their private car, motorcycle or moped for business travel.

New rate for the third quarter of 2026

For the period from 1 July to 30 September 2026, the quarterly indexed mileage allowance is set at:

➡️ €0.4440 per kilometre

This replaces the exceptional monthly indexation that applied between April and June 2026 to reflect fluctuations in fuel prices.

For comparison:

• April 2026: €0.4571/km
• May 2026: €0.4841/km
• June 2026: €0.5055/km
• July to September 2026: €0.4440/km

The lower amount is therefore not the result of a government decision, but simply reflects the return to the normal calculation method.

Two indexation systems remain in place

Belgium continues to operate with two mileage allowance systems:

• Quarterly indexation, which applies in certain sectors.
• Annual indexation, which applies in other sectors or may be chosen voluntarily by some employers.

For reference, the annually indexed mileage allowance is €0.4761 per kilometre for the period from 1 July 2026 to 30 June 2027.

Which rate should you apply?

The applicable rate depends on your Joint Committee (sector) and the collective agreements governing your activity.

Some Joint Committees require a specific indexation system, while others leave employers free to choose between the annual and quarterly systems. Both methods are recognised by the Belgian National Social Security Office (NSSO)and the Belgian tax authorities.

A tax-efficient reimbursement

As long as the mileage allowance does not exceed the official limits, it is considered a reimbursement of business expenses incurred on behalf of the employer.

This means:

• no social security contributions;
• no taxable benefit for the employee;
• a simple and tax-efficient reimbursement for business travel.

Before updating your mileage reimbursement policy, verify which indexation system applies to your sector. If you are unsure, your accountant or payroll provider can help you determine the correct rate.

Sources: Belgian Federal Public Service Policy and Support (BOSA) – Circulars No. 767 and 768, Belgian Official Gazette, and Securex Lex4You.