The supply of Australian government bonds will decline over the next four years and net issuance may even be negative by 2016.Total issuance of Commonwealth government securities in 2011/13 debt issuance is will be around A$38.6 billion, analysis of the budget papers by Commonwealth Bank shows.There will be only $9 billion of  new issuance along with $25.6 billion in refinancing of existing debt. There will also be $2 billion of borrowing through indexed bonds.Part of the funding program in 2013 will be $5.8 billion in Commonwealth government securities that will be labelled "Aussie Infrastructure Bonds".This borrowing is linked in the budget papers to helping fund the corresponding equity investment of the federal government over the year in NBN Co Limited for the construction of the National Broadband Network.Parliament will have to lift the ceiling on government borrowing to $300 billion, from $250 billion. This requirement is already a passing political controversy in a parliament where the governing party lacks a majority in the lower house.Treasury estimated that net debt will peak, in nominal terms, at $145 billion in 2013/14, equal to 8.9 per cent of GDP.