This paper aims to explain how internationally accepted accounting standards are currently applied in the budget statement treatment of the national broadband network (NBN) and how future NBN related transactions are likely to be treated under those standards. Recent media commentary and political debate has concerned the validity of the current accounting treatment of the NBN in the federal government budget statements. This background note (BN) also aims to clarify some of the terms and arguments commonly used during commentary on this topic. For example, the terms on-budget and off-budget, and the notion that the accounting treatment of the NBN is dependent on the rate of return realised by the NBN, are discussed in the section below. The body of the note then examines the accounting treatment of past and potential future NBN related transactions, given three assumed stages of NBN activity. Finally, this BN looks at whether the NBN can be accounted for as an expense item in the budget operating statement and then presents the methodology used to value the government’s equity investment in NBN Company (NBN Co).