Proof of income with documents like Income tax returns, employer's certificate, or Income Tax assessment order. (rupeenomics.com)
«Following a review of financing structures and related party loan pricing, on April 3, 2018, the Australian Tax Office issued amended income tax assessments to ExxonMobil Australia Pty Ltd for the 2010 and 2011 income years and may also have implications for the 2012 to 2017 income years,» said Exxon in its accounts for the 2017 calendar year. (afr.com)
It has also been set as a legal precedent that payment with these coins can not be taken at face value, but rather at their real (metal content) value, for the purposes of income tax assessment. (money.stackexchange.com)