The following factors help establish whether your business is conducted as a partnership:
Copies of any written agreements entered into by the parties or statements of the parties as to the terms of the arrangement;
Copies of partnership income tax returns on which the business income was reported;
Corroboration from the other partner(s); and
Statements from disinterested third parties, such as suppliers, wholesalers, customers, local business people, etc., who are familiar with the manner in which your business was conducted.