Amalgamation tax liability: intra-company supplies during retrospective effective periods remain included in turnover and subject to GST. Amalgamation tax liability arises where companies amalgamated with retrospective effect must include supplies or receipts between them occurring from the retrospective effective date until the date of the order in each company's turnover and pay tax accordingly. For the Act's purposes the companies are treated as distinct legal entities up to the order date, and their registration certificates are cancelled with effect from that date.