Will the tenant pay the difference between the Rent Supplement amount (if granted) and the actual rent? Rent Supplement is calculated so that the person is considered to have a reasonable amount to live on from their Social Welfare payment - for most SW payments, they only have to pay €24 pw themselves. If your rent is much higher than the limit, will they be able to pay the difference to you every month, or will they fall into arrears for the difference?
A lot of Community Welfare areas now look for the tenancy agreement/lease as well as the completed form, so different rent amounts will easily be spotted.