The levying of royal fiscal 'impositions' on overseas trade in 1558 eclipsed varied yet relatively light customs taxation that had existed since at least the thirteenth century. The records of governors that concern this new, relatively lucrative trade taxation are dominated by reports of fraud and evasion. The methods by which merchants and particularly customs officers were said to have embezzled and concealed the taxation, imply organised networks that undertook the fraudulent schemes. This is a curious dominant fixation of Elizabethan ministers, and of those who laboured the issue to them. Such allegations amount to rich seam of source material, and were undoubtedly part of a greater, now perished body of similar records, and they communicate a great deal about Tudor customs taxation - still a mysterious subject. When it came to governing the new customs regime, the principal aim was to standardise and regulate data entered into customs accounts now known as port books. Mistrust of that information became a locus for dramatic allegations and legal activity. Both as practices, but also in a kind of discourse, misbehaviour was coming to be described as the 'corruption' of an essentially public resource. Whether the statements of endemic abuse are true or not, they highlight the structural changes that generated widespread fear of abuse. Historians have ignored such information, arguing that Elizabethan government of customs taxation was too effective to allow for such misbehaviour on any significant scale. However, I show that governance in this sphere was inchoate. The structural changes to English taxation and administration at around this time are outlined using architectural plans, early regional maps and other surviving images. This collection demonstrates the ambition and methods used by governors to augment royal trade taxation from 1558. This was to be achieved by control over strategic locations, along rivers and in English towns, and most strikingly by the control of the information to be submitted and collected at such places by merchants and customs men. We will look at examples of new standardised accounting books from 1565, which for the first time featured voluminous or "big" data. These books were designed in reality to ensure accuracy of customers 'entries', not as statistical devices of a state. There was an epistemological problem to the extension of governance over customs houses, which had previously been virtually free of central oversight. The way the Tudor monarchy came to know its customs taxation in theory would allow specifically for more precise auditing of customs declarations. I demonstrate that fraud and corruption were not side issues, but rather intimate with the very birth of this new 'modern' taxation and administration.