Article 171 of the Belgian Income Tax Code (WIB 92) establishes the regime of separate taxation applicable to certain specific categories of income in personal income tax. This mechanism departs from the general principle of global progressive taxation and is of particular importance to many Belgian taxpayers, notably employees and company directors.
The fundamental principle of Article 171 is that certain income is taxed separately from the rest of the taxpayer’s income, generally at fixed rates that are often more favourable than the ordinary progressive rates. The article sets out a range of separate rates — such as 33%, 30%, 16.5%, 15% and 10% — each applying to a defined category of income. This separate taxation is designed to avoid the occasional over-taxation of exceptional income that would otherwise be pushed into the highest progressive brackets.
Among the income covered by this article are salary arrears (achterstallen), indemnities for the termination of an employment contract (severance pay), certain exceptional bonuses and gratuities, lump-sum replacement income, lump-sum pension capital, and cessation capital gains realised when a business activity ends. The mechanism prevents income that has often accrued over several years but is received in a single instalment from being subject to the highest marginal brackets of the progressive tax.
The applicable separate rate varies according to the nature of the income. For salary arrears and certain indemnities, the rate generally corresponds to the average rate that would have applied had the income been received normally over the years to which it relates. This calculation method, although complex, ensures a degree of tax fairness by avoiding excessive progressivity. Other categories — such as miscellaneous income or specific pension capital — are taxed at their own fixed rate set out in the article.
A built-in safeguard applies: separate taxation is granted only where it produces a lower tax than including the income in the ordinary progressive base would. If the global progressive calculation is more favourable to the taxpayer, that calculation prevails instead.
It is important to understand that the application of Article 171 is not always automatic and may require a specific step by the taxpayer or employer when filing the tax return. Appropriate planning and compliance with administrative formalities are therefore crucial to benefit fully from this regime. Article 171 reflects a broader logic of tax neutrality and temporal fairness, preventing the timing of when income is received from leading to a disproportionate tax burden.
This content is for informational purposes only and does not constitute legal or tax advice. Always consult a qualified tax advisor for matters specific to your situation.