As the UK's tax collection agency, HM Revenue & Customs, is reported to be preparing to reach out to "hundreds" of customers of a bank located in Puerto Rico over possible tax irregularities, financial services industry observers have been pointing out that the bank in question is located in one of five U.S. territories that, like the United States itself, have not signed up to the OECD's Common Reporting Standard (CRS).

When the U.S. Foreign Account Tax Compliance Act finally came into force around the world in 2014 –  four years after it was signed into law by President Obama – the Organisation for Economic Co-operation and Development was preparing its own account information reporting regulations package.

The Common Reporting Standard, as it was to be known as, differed from FATCA in that it was intended to be global, and fully reciprocal – meaning that those countries participating in the collecting and forwarding of information about other countries' resident taxpayer's financial accounts would expect to receive the same data about their taxpayers resident in that country...