Government debt is issued at a fixed, not floating, interest rate. The government can lock in every dollar of stimulus today at an interest rate of 1.49% for the next 20 years. The interest the government pays would remain at 1.49% even if the overnight cash rate rose to 20%. https://twitter.com/TheKouk/status/1254702193086619653

For a sensible take on the implications for the budget and government debt of the COVID-19 crisis, see my recent piece in @theage with @chrisedmond and @BruceJPreston. https://www.theage.com.au/business/the-economy/even-at-130-billion-jobkeeper-package-is-a-steal-20200417-p54kut.html