"Taxpayer" isn't the obligation referred to 14:15 Oct 9, 2011
The obligation referred to in the expression is to report certain types of transaction to the authorities. The most accurate equivalent I've found is "financial bodies subject to reporting requirements". A bit long-winded but it says it. There are similar requirements for non-financial entities, such as estate agents, who could then be called "(other) parties subject to reporting requirements" or "non-financial entities subject to reporting requirements". I was hoping to find shorter alternatives for these expressions. | 
