The calculator now chooses the index months
The standard formula is base rent × new health index ÷ initial health index. The new index is the health index of the month before the anniversary of the lease. For a Flemish main-residence lease concluded from 1 January 2019, the initial index is the health index of the month before the lease took effect (or a rent revision); otherwise the usual rule is the month before the contract was concluded. This compact calculator covers leases signed from 1 February 1994; older regimes should be checked with Statbel.
Recent official Statbel health-index values are bundled locally on the 2025=100 base. If an older required month is outside that snapshot, enter both the initial and new Statbel indices manually using the same base year; the tool refuses a mixed-base calculation.
Important: regional registration and historical EPC/EPB correction-factor rules can affect what may actually be charged. Compare with the official Statbel rent calculator.
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