Taxation is modal: tax may be used to achieve several different social objectives, achievable by other means, both legal and non-legal. Taxation is heavily under-theorised. Juristic definitions of taxation, (in case law, textbooks or economic works) are inevitably thin and without analytical foundation. In particular, there has long been a misconceived notion of taxation as a property obligation rather than what it actually is, a personal monetary obligation. This has spawned a battle on the legitimacy of taxation between libertarians and egalitarians which has been fought on the wrong ground (property rights) entirely. A recognition of taxation as a personal monetary obligation has important practical consequences: First for the categorisation of certain charges (such as NIC) as “taxes” whereas other charges (such as particular tax-related penalties) are not “taxes” despite being contained in a Finance Act; second, the jurisdiction of the First Tier Tribunal (Tax Chamber) must, as a result, accommodate certain notions of legitimate expectation which would not be the case if taxation were a property obligation. Taxation may easily be distinguished not only from property obligations but from other monetary liabilities, such as the obligation to pay contractual monetary consideration for goods or services, a civil penalty, a criminal fine, or tortious damages. The distinction is made clear through the techniques of “individuation”, that is, the description of (here) obligations by reference to the legal norms embedded in the legal material which gives rise to each type of monetary obligation, as exemplified by Raz, Bentham and Kelsen. It is thus that taxation may be “individuated” from other areas of law. And the monetary nature of a tax obligation exposes a profound relationship between monetary obligations and responsibility (so that a purely monetary responsibility dilutes responsibility and also the effectiveness of tax in particular modes).