Methodology for the Belgian Gross/Net calculation

1. Employee social security contribution (13.07%)

The employee's personal social security contribution has been set at 13.07% of gross salary since 1998 (art. 38 § 2 of the law of 29 June 1981). It applies without cap, to both blue- and white-collar workers.

Social security contribution = monthly gross × 0.1307. The monthly taxable salary is the gross less this contribution.

2. Monthly professional withholding tax

The professional withholding tax is the income tax withheld at source by the employer. It is computed on the monthly taxable salary using the official schedule published yearly by SPF Finances (royal decree implementing the Income Tax Code 1992, annex III).

The schedule contains monthly brackets with a base lump sum and a marginal rate. The worker's family situation (single, married with one or two incomes, legal cohabitant) determines which column applies.

3. Reductions for dependents

The withholding is reduced by monthly lump-sum reductions based on the number of dependent children (progressive lump sum), the number of other dependents, and recognized disability for the worker or spouse.

A dependent child recognized as disabled counts double for the lump sum. Amounts are indexed yearly and published in the same royal decree.

4. Monthly net salary

Monthly net = monthly taxable salary − monthly withholding tax (after reductions).

This result does not account for double holiday pay, the 13th month, CCT 90 bonus, or taxable benefits (company car, mobile phone, meal vouchers). These items are handled separately with an exceptional withholding rate.

5. Legal sources

Employee social security: royal decree of 28 November 1969, art. 38.

Professional withholding tax: Income Tax Code 1992 (art. 270 et seq.), implementing royal decree annex III.

Yearly indexation: SPF Finances circulars published annually (typically in December for the following tax year).