Registration under the Agreement satisfies the registration requirements under this Article. A seller who registers under the Agreement within 12 months after the State becomes a member of the Agreement and who meets the following conditions is not subject to assessment for sales tax for any period before the effective date of the seller's registration:
(1) The seller was not registered with the State during the 12-month period before the effective date of this State's participation in the Agreement.
(2) When the seller registered, the seller had not received a letter from the Department notifying the seller of an audit.
(3) The seller continues to be registered under the Agreement and to remit tax to the State for at least 36 months.