The law requires you to notify the landlord of a defect without delay. Anyone who stays silent and simply pays less risks losing the right to reduce and building arrears.
✓ Verified: 01/08/2026
WHAT TO DO
This is the step at which the right is most often lost. The reduction arises by law, but the same law demands immediate notification — and silence turns a strong position into arrears.
Local tenants’ associations of the Deutscher Mieterbund↗ help with wording and assessment; where conflict with the landlord arises, advocado↗ offers an initial legal assessment.
I complained verbally at chance meetings for three months and thought I had notified them. Nothing existed in writing, and the dispute started from zero.
Send the notification with proof of dispatch and keep a copy. One document settles the entire argument about which date the clock runs from.
Because the law obliges the tenant to report a defect without delay. Failing to do so makes you liable for the resulting damage and can forfeit the right to reduce for the period of silence. Notification is not courtesy but a precondition.
In writing, with a description and a date, and in a way that leaves proof of sending. A conversation on the stairs or a messenger note is nearly impossible to evidence six months later — and that is exactly what gets disputed.
Specifics rather than judgements: which defect, in which room, since which day, and how it obstructs use. Attaching dated photographs helps, as does setting a reasonable deadline for repair.
Technically the reduction arises by law, but acting without notification is risky: a silent cut looks like arrears and, once they accumulate, gives the landlord grounds to terminate. Notification first, everything else after.