4. COLLECTION OF TAX
As a rule, tax is collected by deduction at the source at the time when the income is paid. It is paid into the Treasury within a fortnight of the attribution or payment of the income; in default of payment within this time-limit, the Treasury is entitled to charge interest on the sum due at the rate of 6 per cent per annum.
The provinces and communes may only levy additional tax (centimes additionnels) on income from capital invested in Belgium.