There may be no great shortage in Australian government bonds to fill the liquidity books of banks, even if net debt of the federal government moderates in line with scenarios presented in last night's federal budget.Over 2016/17, the face value of Commonwealth government securities on issue "is expected to reach a within-year peak of A$498 billion," Treasury said in budget papers. Over the forward estimates, the face value of CGS on issue is projected to rise to a within-year peak of $593 billion in 2019/20. By 2026/27, the face value of CGS on issue is projected to rise to $640 billion.Treasury said that, over the forward estimates, net debt is projected to peak at 19.2 per cent of GDP in 2017/18. "Over the medium term, net debt is projected to decline to 9.1 per cent of GDP ($264 billion) in 2026/27," it said.