Marketplace Equity Act of 2011 - Authorizes states to require all sellers making remote sales to collect and remit sales and use taxes with respect to such sales into the state, without regard to the location of the seller, if such states implement a simplified system for administration of sales and use tax collection for remote sellers. Requires such a system to include, at a minimum: (1) an exception for remote sellers with gross annual receipts in the preceding calendar year from remote sales not exceeding $1 million in the United States or not exceeding $100,000 in the state, (2) a single sales and use tax return for use by remote sellers and a single revenue authority within the state with which remote sellers are required to file a tax return, and (3) a uniform tax base throughout the state.
Defines "remote sale" as a sale of goods or services attributed to a state with respect to which a seller does not have adequate physical presence to establish a nexus so as to allow such state to require such seller to collect and remit taxes.