Raising rent to the local comparative level is not a unilateral right but a consent procedure – miss a step and you lose months.

"The landlord may demand consent to an increase of the rent up to the customary local comparative rent if the rent has remained unchanged for 15 months at the time the increase is to take effect."

— § 558 (1) BGB (translated)

Preconditions

  • Waiting period: 15 months since the last increase; the demand may arrive at the earliest one year after.
  • Cap: 20% within three years, 15% in strained markets (§ 558 (3)).
  • Justification (§ 558a): rent index, rent database extract, expert opinion, or three comparable flats. Where a qualified rent index exists, it must at least be cited.

The procedure

  1. Demand in text form, with justification, to all tenants.
  2. The tenant's consideration period: until the end of the second month after receipt.
  3. Consent in full, in part – or silence. The landlord then has three further months to sue for consent (§ 558b (2) BGB); afterwards the demand is spent.
  4. Upon consent, the new rent applies from the third month after the demand's receipt.

Practice error number one: cap miscalculations from forgotten earlier increases – a clean per-unit rent ledger prevents it.