The bijzonder tarief, or special wage-tax rate, is the rate used by Dutch employers to withhold wage tax and national insurance on non-recurring pay. Typical examples include performance bonuses, overtime lump sums, the 13th month, holiday allowance, severance settlements, and back-pay corrections.
The rate is set individually for each employee based on their previous calendar year's taxable wage. The Belastingdienst publishes the bracket table annually, together with an adjustment percentage (verrekeningspercentage) that corrects for the interplay between the labour tax credit (arbeidskorting) and the general tax credit across income levels. Payroll software applies both elements automatically.
Because the rate is an estimate of the employee's true marginal rate, the final settlement happens in the annual income tax return. Employees at the top of the bracket structure often see a refund or an additional assessment after filing, depending on how their actual annual income compared with the projection.