The rule in plain words

Take your business profit, subtract the entrepreneur deductions (such as the zelfstandigenaftrek), and then 12.7% of what remains simply stays untaxed. Zero conditions, zero hour thresholds, zero application — the return applies it by itself.

A worked example

Profit €80,000, minus €1,200 zelfstandigenaftrek leaves €78,800; the exemption removes 12.7% (€10,008), so €68,792 enters box 1. At the marginal rates that saves several thousand euros a year — a structural part of why the sole-trader form stays attractive at moderate profits.

The flip side

The exemption works on the profit in both directions: in a loss year it reduces the deductible loss by the same percentage. And it belongs to income-tax entrepreneurs only — a BV (besloten vennootschap, the Dutch private limited company) knows corporate tax and its own regimes instead.

Where it sits in the BV question

The exemption is one of the sole trader’s structural advantages the BV has to beat. The full comparison across profit levels stands in BV versus sole proprietorship; the tipping-point arithmetic in the box system explainer.