Discharge of liability requires furnishing prescribed forms to compute and discharge tax; failure preserves standard tax liability. A dealer eligible to discharge liability under the continuing works contract provision must furnish a prescribed statement with supporting documents in the specified form with the first VAT return after rule notification and compute tax in the prescribed manner; failure to file the complete statement within the prescribed time prevents discharge under that provision. Thereafter the dealer must submit a prescribed computation form with each periodic VAT return up to the prescribed cut-off, and returns without the duly completed computation form are invalid and incorrect.