As is where is basis regularization: lower GST payments accepted as full discharge; higher-paying taxpayers not refunded. Regularization on an as is where is basis accepts the tax position declared in taxpayers' returns where competing entries or interpretations produced different GST rates; payments at the lower competing rate or a claimed exemption are treated as full discharge for the period regularized, taxpayers who paid the higher rate receive no refund, and where regularization adopts a higher rate it does not cover non-payers who must have the applicable tax recovered.