This summer, the senior management of one of Asia’s largest financial groups is quietly mulling a potentially explosive question: could it organise some of its subsidiaries so that they could stop handling all US Treasury bonds?

Their motive has nothing to do with the outlook for the dollar. Nor does it reflect fears about the US debt ceiling (or the risk that the US will soon default if it fails to raise the legal limit on bond issuance).

Instead, what is worrying this particular Asian financial group is tax. In January 2013, the US will implement a new law called the Foreign Account Tax Compliance Act (Fatca), that forces all global financial companies to report details to the IRS, the US tax authority, of any clients linked to the US with more than $50,000 in an account. These rules, quietly passed by Congress last year, would partly put the responsibility on the bank or asset manager – not just the individual – to make this filing.