The invention relates to a method for ascertaining valid address codes for valid address data using an address dictionary which stores all the permissible address details with the associated address codes in searchable form for a particular territory. The address dictionary is automatically searched using the valid address data and all the coarsening stages respectively derived therefrom. The address codes contained in the dictionary entries found for each valid address, including all the associated coarsening stages, are output as a valid address code.