The Parliamentary Budget Office has rejected suggestions that its modelling of Labor’s dividend imputation policy was second-rate, undermining Scott Morrison’s attempt to discredit the opposition.

It is the second time in 10 months that the PBO has had to correct the public record after being dragged into one of Morrison’s political attacks.

News Corp papers published a story on Monday claiming Labor was facing a “$10bn black hole” in its savings plan to abolish franking credit refunds for retirees.

According to the reports, new Treasury analysis had found that Labor’s policy costing had failed to account for the fact that shareholders would change their behaviour in response to its proposal, by rearranging their affairs to avoid the new tax, so Labor would collect $10bn less over a decade than it had been claiming.

Morrison said the analysis demonstrated that Labor had over-estimated the revenue it expected to collect from its policy because it hadn’t thought it through properly.

“Treasury’s costing is the product of a thorough assessment of Labor’s proposal, including likely behavioural impacts of individuals rearranging their affairs to avoid the new tax, and follows consultations with external stakeholders, as well as analysis of relevant available data,” Morrison said in a statement.

But the Parliamentary Budget Officer, Jenny Wilkinson, has publicly rejected any suggestion that the PBO’s costing of Labor’s proposal was second-rate.

“The PBO brings our best professional judgement to the independent policy costing advice we provide,” she said in a statement on Monday evening.

“We have access to the same data and economic parameters as the Treasury and draw upon similar information in forming our judgements.

“We stand behind the PBO estimates that have been published by the ALP in relation to this policy, noting that all policy costings, no matter who they are prepared by, are subject to uncertainty.”

Wilkinson said the PBO was explicit about the judgements and uncertainties associated with individual policy costings, and the PBO always took into account current and future policy commitments, as well as behavioural changes, in its policy costings.

“In this case, as outlined at the recent Senate Estimates hearings, these included the superannuation changes announced in the 2016–17 Budget and the scheduled company tax cuts,” she said.

“In addition, the PBO explicitly assumed that there would be significant behavioural changes that would flow from this policy, particularly for trustees of self-managed superannuation funds.

She then reminded the government the PBO was established as an independent institution in 2012 with broad support from the parliament, and the purpose of establishing the PBO was to improve the public’s understanding of, and confidence in, policy costings and enable policy debates “to focus on the merits of alternative policy proposals.”

Her reassertion of the PBO’s integrity follows a similar effort last year.

In August, the PBO issued a public statement rejecting reports it had produced “new modelling” that showed Labor’s policies would increase the tax burden on households by more than $100bn.

Morrison’s office had dropped that story to newspapers on a Sunday afternoon, to be published on the Monday morning, and told the journalists the new figures had come from “independent modelling by the PBO and Treasury”.

Wilkinson responded publicly: “References in the media this morning to modelling being released today by the Parliamentary Budget Office (PBO) are incorrect,” she said in a statement.

Morrison later admitted on Sky News the new figures were not from new PBO modelling but were an extrapolation from some of the PBO’s modelling from 2016.

Records show the PBO has had to correct the record at least four times since 2013.