Deemed let out property is assumed to be given on rent for income tax purpose.
If a taxpayer owns multiple properties, only one can be claimed as Self-occupied. The remaining properties will be considered as Deemed Let Out. This means that the property will be taken as rented property even if it is not given on rent. Tax on the notional rent will be charged for income tax purpose.
However, you have the option to select which property you want to take as Self Occupied.