🇧🇪 Cross-border taxation in Belgium
Belgium exempts the Luxembourg salary but keeps it to set the rate applied to the household's remaining income.
Mechanism applied: Exemption with progression reserve
The Luxembourg side, for everyone
Taxed at source
A salary paid by a Luxembourg employer is taxed in Luxembourg, withheld monthly on the payslip. The country of residence does not tax it — it only takes it into account, differently in each case.
Tax class and withholding card
The class (1, 1a or 2) depends on family situation and sets the scale applied. It appears on the withholding card the employer must hold: without it, tax is withheld at the maximum rate and only corrected afterwards.
Assimilation to resident status
A non-resident whose income comes mostly from Luxembourg can ask to be taxed as a resident. That opens the deductions reserved for residents — loan interest, insurance, contributions. It is the lever cross-border workers most often leave unclaimed, and it has to be requested, not granted automatically.
Social contributions
They go to Luxembourg (CCSS) as long as telework from the country of residence stays under the affiliation threshold. Health cover then sits with the CNS, including for care received in the country of residence.
Source: Administration des contributions directes
🇧🇪 The country-of-residence side
The return is still compulsory
Exempt income is declared, in the box provided for foreign-source income. That declaration is what triggers the exemption: without it there is nothing to exempt.
Communal surcharges
Belgian communes levy an additional percentage on personal income tax, and the rate varies noticeably from one commune to the next. On exempt income the base is largely neutralised — but the communal rate remains a criterion for anyone with other Belgian income.
Source: SPF Finances
This page describes the architecture, not the scales: rates, bands and allowances change every year, and a stale figure here would cost the reader money. For amounts, go to the source — and have your own case checked.
Structure verified on 2026-08-17