1. A method for preparing a tax return for a user, comprising: collecting tax data items without user intervention by: identifying, using a processor of a computer system and by applying a plurality of inference rules based on information of the user, a first document and an entity configured to maintain the first document; identifying an access mechanism for accessing the first document from the entity and obtaining a downloaded copy of the first document based on the access mechanism; retrieving, using the processor, a first tax data item from the first document by applying the plurality of inference rules based on the downloaded copy; obtaining a scanned image of a second document; and retrieving, using the processor, a second tax data item from the second document by applying the plurality of inference rules based on the scanned image; generating, using the processor, a partially completed tax return by populating a tax form of the tax return using the first and second tax data items and calculating a preliminary tax liability therefrom; and displaying the partially completed tax return comprising the preliminary tax liability to the user.
4. The method of claim 1 , wherein access credentials to a user account at the entity were obtained from the user and saved in a user profile during preparation of a prior year tax return, wherein the access mechanism comprises the access credentials, and wherein the first document is identified based on the user profile.