From the RTB Website.
The RTB Rent Register should be a landlord’s main reference point when setting rent. If a landlord wants to set a rent higher than comparable examples from the Register, they must justify that it represents market rent. To do this, they should provide additional evidence, such as expert valuations.
While a landlord can reference additional sources, they are legally obliged to consider the RTB Rent Register and this should carry significant weight in their decision.
A landlord must keep clear records to support their rent setting decision. They may need to provide the documents as evidence if there is a dispute case or investigation by the RTB in future. Failure to follow rent setting rules is an offence under the Residential Tenancies Act.
These are the important points to my mind:
1. If we want to go higher than the RTB chosen comparables, we have to obtain an expert valuation.
2. The RTB Register carries 'significant weight' ie it is the most important source
3. High rent will be the subject of an RTB investigation and the tenant can dispute it also
4. Too high a rent is a criminal offence with a prison term and/or a fine