Net rental yield is the figure that actually matters, because it reflects what lands in your pocket. The formula is: (annual rent minus annual running costs) divided by the all-in purchase price, multiplied by 100. The all-in price includes the property plus registration duties (12.5% on a Walloon investment purchase, wallonie.be, 2025) and notary fees.
The running costs to subtract are the précompte immobilier (Walloon property tax, based on the indexed cadastral income at a base rate plus large municipal and provincial surcharges, wallonie.be), building insurance, non-recoverable common charges where there is a syndic, ongoing maintenance, any management fee, and a provision for rental vacancy and unpaid rent. Together these often consume 25% to 40% of gross rent.
A worked example: an apartment bought all-in for 170,000 euros and let at 750 euros a month produces 9,000 euros gross. Subtract, say, 1,000 euros précompte, 300 euros insurance, 900 euros charges and maintenance, and 600 euros for management, and net income is about 6,200 euros. Net yield is 6,200 divided by 170,000, roughly 3.6%.
The counter-intuitive truth is that the gap between gross and net is where investments succeed or fail. A national benchmark puts city gross yields at 3.5% to 5% and net returns at just 2.5% to 3.5% (estate-value.be, 2026). A cheaper Charleroi flat with a 7% gross can still beat a Namur flat with a 5% gross on a net basis, but only if its costs and rental vacancy stay under control.
At a glance
| Line | Example amount |
|---|---|
| Annual rent (750 euros x 12) | 9,000 euros |
| Less précompte immobilier | 1,000 euros |
| Less insurance | 300 euros |
| Less charges and maintenance | 900 euros |
| Less management and rental vacancy provision | 600 euros |
| Net annual income | about 6,200 euros |
| All-in purchase cost | 170,000 euros |
| Net yield | 6,200 / 170,000 = about 3.6% |
National net benchmark: 2.5% to 3.5% (estate-value.be, 2026).