An eviction notice may be invalid if it uses the wrong notice period, is not in the prescribed form, gives an incorrect termination date, or fails to state a required reason for ending the tenancy. It may also be defective if it was not served correctly, or if the landlord failed to send a copy to the Residential Tenancies Board (RTB) on the same day. Additional rules can apply to fixed-term tenancies, rent arrears and other breaches. The RTB ultimately decides whether a notice is valid based on the tenancy’s facts, so consider getting advice from a solicitor or Threshold.