company', not a 'corporation', that is the subject of corporation tax. The two expressions are 'not synonymous',5 since the corporation tax definition of a company both includes and excludes certain entities that are corporations under the general law. The central example of a company for corporation tax purposes is the corporation, and the key example of the corporation is the 'limited company' registered under the Companies Acts. Limited companies may be private ('Ltd') or public ('plc').6 Below, 'company' refers to a limited company of either type unless the context indicates otherwise.