Term used in the German VAT Act (§ 1 UStG). Taxable transactions are transactions that are subject to national VAT. They may be taxable or tax-exempt. Taxable transactions include the supply of goods and other services that a businessperson performs in Germany for a fee as part of his/her business operations, as well as the importation of goods from a third country to Germany or intra-Community purchases.

Source: UStG, edited (only available in German)