In Belgium
The lease notice and the notice to quit (renon) are two terms designating the same legal reality: the formal notification of lease termination.
The notice must comply with requirements of form (registered letter or bailiff’s writ) and timing (3 months’ notice for the tenant, 6 months for the landlord in a 9-year lease).
The landlord’s notice must state the grounds for termination. A notice without grounds or with vague grounds is null. The tenant’s notice requires no justification.
Practical example
On 10 February, Lucie sends a lease notice by registered letter to her landlord. The 3-month notice period starts on 1 March and ends on 31 May. Lucie must pay rent until 31 May and return the keys on that date. Since she is in her 5th year of lease, no compensation is due.