In Belgium

Tacit renewal applies differently depending on the type of lease:

9-year lease. If neither party gives notice at least 6 months before the end, the lease is automatically renewed for successive 3-year periods under the same conditions.

Short-term lease. If the lease is not terminated at expiry and the tenant stays, it is reclassified as a 9-year lease from the start date of the original contract. This is the main trap.

Student lease. Renewal depends on the Region. Generally renewed for one year if neither party gives notice.

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Warning
A 1-year short-term lease tacitly renewed beyond 3 years total is automatically reclassified as a 9-year lease, retroactively from the start date. The landlord loses all flexibility. Carefully note expiry dates in your calendar or management software.

Practical example

Pierre lets his studio with a 1-year short-term lease. At expiry, he does not react. The tenant stays. The lease is renewed for another year. Then another. After the 3rd year, if Pierre has still done nothing, the lease is automatically reclassified as a 9-year lease retroactively.