The $38 trillion U.S. Treasury debt is under close scrutiny by markets and academics alike. Assessing its sustainability, however, is far from straightforward. It wouldn’t be for any debtor — but it is particularly complex for the U.S. Treasury. It is tempting to approach the question as one would a corporate or household balance sheet: by asking whether the current value of the debt can be repaid in the future through dollars raised from taxation, net of public spending. […]