As is where is basis in GST regularisation treats lower-rate payments as full discharge and prohibits refunds to higher payers. Where genuine doubt arises from competing tariff entries or divergent interpretations, past returns and payments made by taxpayers at a lower competing rate (including nil rate under an exemption entry) will be accepted as full discharge of tax liability for the period regularized on an 'as is / as is, where is' basis; taxpayers who paid a higher rate are not entitled to refunds, and regularisation does not protect cases where no tax was paid, in which event the appropriate tax will be recovered.