THERE'S more than the outcome of an election hanging on the costing exercise now under way in the Treasury and Finance departments.

There's also the future of two Perth-based accountants, the reputation of the Institute of Chartered Accountants, the public position of at least one high-profile academic institution, and the future of the entire auditing industry and the consultants who hang off it lending the name of auditors to unaudited and unverified political documents.

Let's go back 10 days or so before the election when Opposition Leader Tony Abbott started hinting he might not submit his policies for costing by Treasury and Finance in accordance with the Charter of Budget Honesty but might instead have them ''independently and authoritatively costed by a third party''.

We now know the third party was the Perth office of a chain of independently owned accounting firms that had been quietly working with the Coalition since mid-June, back when Kevin Rudd was prime minister.

WHK Horwath specialises in small and mid-size companies - in the words on its website, those ''on a path of growth''. As far as is known, it had no experience of modelling economy-wide tax and spending changes, the sort of work done with distinction by Australia's Treasury and several private firms comprised of former Treasury staff in Canberra.