The Household Charge is an annual charge which is payable by owners of residential property. It is a matter for owners of residential properties to register and pay the Household Charge on or after 1st January 2012. Registration is done at https://www.householdcharge.ie/default.aspx
The charge is €100 per residential property, and it must be paid by 31 March 2012 or penalties will apply.
It applies to each residential property, and is separate from the NPPR charge of €200.