The standard contact information necessary for owner and admin contact are the following:

Organisation
First Name
Last Name
Address
City
State/Prov
Postal Code/Zip
Country
Telephone
Fax
Email

With the exception of the fax number, which can be left blank if none is available, all of these fields are required. If there is no organisation applicable, the name of the individual owner must be entered in that field. If the owner is a company rather than an individual, the first and last name listed should be an officer of that company.

The new owner will need to provide the above to the current owner for both the registrant and the admin contact fields, or if the owner and admin contact information is the same to indicate that to the current owner. Again it is important to be clear about this at the outset to prevent potential problems in the future.