Under US law, a tax is defined as a compulsory payment pursuant to the authority of a foreign country to levy taxes. While this definition is somewhat circular, it does require (i) a payment, (ii) that is not voluntary,(iii) to a foreign country, (iv) pursuant to its authority to levy taxes
Publication Information & Recommended Citation
Avi-Yonah, Reuven S. "Annex 3: Definition of 'Tax' in US Law." In The Concept of Tax, edited by B. Peeters et al., 327. EATLP International Tax Series, 3. Amsterdam: European Association of Tax Law Professors, 2005.