The Australian Office of Financial Management (AOFM) on Tuesday said net issuance would be around A$28 billion, after accounting for maturities of A$31 billion and A$15 billion of buy backs. Some A$42 billion of debt has already been sold this financial year, leaving A$32 billion still to be issued.

The revised numbers follow the government's mid-year fiscal update released on Monday.

The agency said it plans to issue a new November 2029 Treasury Bond line via syndication. Two syndicated tap issues of existing long-dated bond lines have been held to date in 2017-18 and further issues were planned.

A new May 2041 bond line is also planned to be issued in the first half of 2018/19.

Around A$5 - A$6 billion of Treasury Indexed Bonds will be issued for 2017/18, with A$4 billion already sold.