Wis. Stat. § 77.524 — Seller and 3rd-party liability

77.524(1) (1) In this section:

77.524(1)(ag) (ag) “Agent” means a person appointed by a seller to represent the seller before the states that are signatories to the agreement, as defined in s. 77.65 (2) (a) .

77.524(1)(am) (am) “Certified automated system” means software that is certified jointly by the states that are signatories to the agreement, as defined in s. 77.65 (2) (a) , and that is used to calculate the sales tax and use tax imposed under this subchapter and subch. V on a transaction by each appropriate jurisdiction, to determine the amount of tax to remit to the appropriate state, and to maintain a record of the transaction.

77.524(1)(c) (c) “Seller” has the meaning given in s. 77.65 (2) (e) .

77.524(1g) (1g) “Certified service provider” means an agent that is certified jointly by the states that are signatories to the agreement, as defined in s. 77.65 (2) (a) , and that performs all of a seller’s sales tax and use tax functions related to the seller’s retail sales, except that a certified service provider is not responsible for a retailer’s obligation to remit tax on the retailer’s own purchases.

77.524(2) (2) A certified service provider is the agent of the seller with whom the certified service provider has contracted and is liable for the sales and use taxes that are due the state on all sales transactions that the provider processes for a seller, except as provided in sub. (3) .

77.524(3) (3) A seller that contracts with a certified service provider is not liable for sales and use taxes that are due the state on transactions that the provider processed, unless the seller has misrepresented the type of items that the seller sells or has committed fraud. The seller is subject to an audit on transactions that the certified service provider processed only if there is probable cause to believe that the seller has committed fraud or made a material misrepresentation. The seller is subject to an audit on transactions that the certified service provider does not process. The states that are signatories to the agreement, as defined in s. 77.65 (2) (a) , may jointly check the seller’s business system and review the seller’s business procedures to determine if the certified service provider’s system is functioning properly and to determine the extent to which the seller’s transactions are being processed by the certified service provider.

77.524(4) (4) A person that provides a certified automated system is responsible for the system’s proper functioning and is liable to this state for tax underpayments that are attributable to errors in the system’s functioning. A seller that uses a certified automated system is responsible and liable to this state for reporting and remitting sales and use tax.

77.524(5) (5) A seller that has a proprietary system for determining the amount of tax that is due on transactions and that has signed an agreement with the states that are signatories to the agreement, as defined in s. 77.65 (2) (a) , establishing a performance standard for the system is liable for the system’s failure to meet the performance standard.