How did the budget and the responses to it stand up to scrutiny? In the case of Tony Abbott, not very well.

The Budget created the usual amount of debate amongst politicians and the media. But how did the National Broadband Network fare?

At first, the NBN drew little debate beyond the usual Coalition attacks in Tony Abbott's budget reply speech and Malcolm Turnbull's inevitable criticism of the government's spending. But, in the week since, Turnbull has followed his initial response with a change to his NBN position that may put the battle over the NBN into completely new territory.

What Labor said

When it comes to the NBN, Wayne Swan's fifth budget was largely a regurgitation of the many facts that have already been circulated about the NBN rollout. The project was mentioned 17 times in the Budget papers, highlighting both the status of the project and a number of ancillary projects being run in conjunction with other government portfolios.

The NBN featured prominently in the budget's Statement of Risks section, with unquantifiable risks including the government's indemnity for NBN Co directors against liability from their involvement in the Telstra negotiations or any failure of the government to meet its NBN Co funding obligations. Also noted as a risk was the government's guarantee to Optus under its NBN Co agreement, which hinges on precedent conditions that had not been satisfied as of 31 March; "the guarantee had therefore, not come into effect", the Budget notes.

Interestingly, the government has also flagged an unquantifiable risk from potential but not-yet-initiated legal proceedings around its 13 March 2009 cancellation of the previous OPEL broadband plan. No such proceedings had been filed by 31 March, although the lingering presence of OPEL confirms that it looms large in the minds of representatives of both sides of politics.

Quantifiable risks included the estimated $1.8 billion identified as liabilities should the NBN rollout be terminated the government forced to terminate its Equity Funding Agreement with NBN Co. Also listed was the government's guarantee to Telstra around NBN Co's financial obligations to Telstra; as at 31 March, the project had generated liabilities of approximately $209 million. These liabilities will persist until the NBN is fully operational and has achieved specified credit ratings over a period of two continuous years.

The NBN featured in the Budget's Major Assets and Liabilities section, with the interesting note that delays to finalisation of the Telstra contract meant NBN Co will only have drawn down $2.1 billion from the government in 2011-12 rather than the $3.4 billion. The budget expects to provide $20.1 billion in equity to NBN Co between 1 July this year and the middle of 2016.

Other Budget measures related to programs that have largely already been announced. There's $5m for a three-year pilot program to deliver virtual English tuition to new migrants over the NBN; $4.9m over three years to provide NBN-delivered support for hearing and/or vision impaired children in regional and remote Australia; and a $4m, two-year program to provide legal assistance to regional and remote Australians via the NBN. There's also $2.4m over two years to help "national cultural institutions" explore the NBN's possibilities, and $20m on an education campaign designed to "improve public misunderstanding, address misconceptions and provide updated information about the NBN", particularly in regional and remote areas. There's also a $6.2m allocation with the Department of Human Services for a four-year Digital Productivity pilot program exploring the delivery of face-to-face medical services from remote specialist consultants.

What the Opposition said

Tony Abbott's speech broadly slammed the government for its "cooked books" approach and lack of a plan for economic growth, then mentioned the NBN in the context of the Coalition's mooted $50 billion in savings claims. "Why spend $50 billion on a National Broadband Network so customers can subsequently spend almost three times their currently monthly fee for speeds they might not need? Why dig up every street when fibre to the node could more swiftly and more affordably deliver 21st century broadband?

Disregarding subjective debates over what customers do and don't need, or the viability of the Coalition's FttN plan, there are several obvious factual inaccuracies in these statements: for example, already-announced NBN broadband plans are broadly in line with current ADSL pricing; and the NBN is currently estimated to cost around $36 billion, with just $27 billion of direct government funding over the next decade - and even that will come back to the public purse once the NBN is completed and sold.

Sticking with a broad policy platform announced earlier this year, Abbott repeated his third factual error in a subsequent interview on the Nine Network, arguing that "the Government will be spending something like $5 billion in the next financial year digging up streets. I just don't think that is necessary." In fact, the NBN Co has dug up next to no streets, anywhere; the main purpose of its $11b contract with Telstra was to avoid having to do that. Because that contract had not yet been finalised, last year NBN Co even ran NBN fibre overhead in early-release sites rather than digging up streets.

That the NBN was mentioned at all in Abbott's speech flew in the face of this determination, which has previously muted arguments that the NBN should be handled as a budget expense and would seemingly have precluded its mention in the context of a budget response. Nonetheless, Malcolm Turnbull took the Opposition argument to Parliamentary Question Time, arguing that if the NBN were an on-budget expense it would have turned the 2012 budget into a deficit of "at least 12 billion".

This is all just moot speculation, however: Labor has long maintained that the expenditure on the NBN is being treated as an 'off-budget' equity investment, which is subject to different accounting rules. In January, this approach was validated in a research note by Brian Dalzell from the Economics Section of the Parliamentary Library, who discouraged the use of the terms 'on-budget' and 'off-budget' but nonetheless confirmed that what Labor has done is correct:

In the budget statement, the NBN is accounted for as a financial asset (equity investment) under the 'investments in other public sector entities' line item of the balance sheet... Money transferred to NBN Co cannot be classified as an expense under currently accepted accounting standards. It is accounted for as a financial asset on the balance sheet (an 'investment in other public sector entities'), as opposed to an expense item on the operating statement. An eventual gain or loss on the government's equity investment in NBN Co is accounted for in the operating statement as an expense, but this does not affect the fiscal balance measure.

Even as Abbott hit the airwaves to talk down the Budget, discussion continued at a steady pace, with much criticism of Tony Abbott's statements - from Stephen Conroy and others - until Malcolm Turnbull came out with a surprising response to Budget figures suggesting it would cost a Coalition government at least $1.8 billion in break costs were it to assume government and try to halt the NBN as currently envisioned. Although Turnbull has previously claimed it would be entirely possible to shift gears on the NBN, his response to the $1.8 billion figure was to concede that the Coalition might not end up changing existing NBN contracts at all.

"We're not about breaking contracts, even if they've been entered into unwisely," he said after a post-Budget luncheon in which he said the Coalition was "not ruling out fibre to the premises".

"If the contractual commitments have been made, the Commonwealth has to honour them," he said. "There are termination provisions in some contracts... but really, I don't anticipate that happening.

What others said

The industry had been bracing itself for a slim Budget, and the government met anticipations by delivering relatively little for IT. This left the media clamouring for something to talk about - and Abbott's questionable numbers put him directly in the firing line.

Observers searched for creative ways to fact-check and describe the Coalition's response, variously warning that Abbott had dredged up the "ghosts of ideologies past"; calling him the "philosopher-prince of the assertion-based community"; and describing it as "all values, no costings".

Others said Abbott had misled the public and was "consciously lying" about the cost of the NBN; had "fire[d] bullets but misse[d] detail" and questioned why Abbott doesn't seem to be able to get straight facts from his IT policy advisor Malcolm Turnbull. The ABC's Annabel Crabb was none too impressed either, calling the Budget "a nuts-and-bolts affair" while calling Abbott the 'Budget-Smuggler' and terming his Budget replies and promises "unrealistic".

Analysis picked out the Budget "whingers and losers" while others called Abbott's response a "Magic Pudding Budget Plan". And telecommunications analyst Paul Budde was equally unconvinced, slamming Abbott's "ridiculous statements".

"The question is, who is fudging more?" he told ABC Technology and Games. "The NBN is not a budget item; it is an investment over 10 years. There won't be any budget savings coming from cancelling the NBN. It is also interesting to note that Turnbull and Abbott spread totally different messages on the issue of the NBN. There seems to be a severe rift between the two of them."