Belgian expat tax regime: circular letter published

On 1 April 2026, the Belgian tax authorities have published circular letter nr. 2026/C/51 regarding the changes to the specific tax regime for inbound taxpayers and researchers (Dutch | French). The circular letter clarifies the changes implemented by the law of 18 December 2025.

Changes applicable as of 2025

The law of 18 December 2025 implemented some important changes to the expat tax regime:

• Increase of the maximum percentage of costs proper to the employer (CPE) from 30% to 35%; 

• Abolishment of the maximum yearly ceiling of EUR 90,000 for the CPE; 

• Reduction of the minimum yearly salary threshold for inbound taxpayers from EUR 75,000 to EUR 70,000 (not applicable for researchers).
  

This law applies retroactively to all remuneration earned as of 1 January 2025.

The increase to 35% CPE has not been accepted by the social security authorities and therefore, the additional 5% CPE can be granted free from taxation but will remain until further notice subject to social security contributions. 

Clarifications of the circular letter

The circular letter provides for some example cases where the retroactive application of the law as of 1 January 2025 has an impact. 

All inbound taxpayers/researchers 

All inbound taxpayers/researchers can benefit from the more beneficial amount of CPE and the abolishment of the salary threshold (for inbound tax payers), as of 1 January 2025, even if they were already subject to the expatriate tax regime before that date. This is always optional. Practically this means:

• Their contract may be amended within 3 months after publication of the circular letter, to retroactively amend and implement the tax benefits. The contract may stipulate that these changes apply retroactively as of 1 January 2025.
  • E.g. increase of the CPE to 35%, without any limitation 
  • E.g. decrease of the base salary up to a minimum of EUR 70,000
• Any amendments to the base salary could also have an impact on other topics e.g. build-up of supplementary pensions, legal pension pay-outs, vacation pay and replacement income.

• In case of retroactive amendment, the salary form 281.10 for 2025 will have to be amended and the monthly withholding tax returns for 2025 will also have to be amended.

• For all requests for extension of the expatriate tax regime, or a change in employer after 1 January 2025, the tax authorities will take into account the new conditions and ceilings.

Inbound taxpayers who have started working in Belgium during period 1/01/2025 to 9/01/2026

For inbound taxpayers with a salary between EUR 70,000 and EUR 75,000, but who fulfilled all other conditions, a new application for the expatriate tax regime can be submitted within 3 months after 9 January 2026 (so until 9 April 2026).

The new application will have to prove that all conditions for the tax regime, including the minimum threshold of EUR 70,000, were fulfilled at the start of the Belgian employment. This exception for late filing is applied in a restricted way, e.g. taxpayers with a salary exceeding EUR 75,000 or who started before 1 January 2025 do not qualify as they should have filed an application within the original deadline.