Banks have little more than the weekend to marshal arguments to shape or deflect the planned levy on their wholesale liabilities.Treasury officials conferring with chief financial officers of the five biggest banks yesterday yielded little or nothing, making clear the industry must conform to a tight timeline for submissions on matters of detail (due by Monday), and must then react and comment by Thursday on an exposure draft of the bill planned to be ready by Wednesday.If anything, the main takeaway on the part of bank CFOs seems to be a sense that Treasury officials had worked on the new levy for a very, very short period of time ahead of the budget.The brevity of the text used to rationalise the new tax in the principal budget document and other presentation matters are the basis, for some around the banking sector anyway, that the liability levy was a very, very last minute decision of the government and one reached without the preparation typical of such a measure.Of more moment to banks at and following the meeting is their lack of certainty, fanned by Treasury uncertainty, over complex technocratic matters prepared by the banks.The CEO of the Australian Bankers' Association, Anna Bligh, in a media release said there were more than 20 important issues that were unable to be addressed.David Lynch, chief executive of the Australian Financial Markets Association, an observer of the wrangling for now, framed some of the principled arguments that might be debated over coming days over specialist matters."The financial system needs tax arrangements that are internationally competitive and non-distortionary between different types of institution and between different financial products," Lynch said.  "The announced levy on major banks is inconsistent with this approach and sets a poor policy precedent."While banks set out to blindside Treasury with arcane matters at the heart of bank funding and the flow of these liabilities from cash management practices of big corporations and institutional investors, along with the tedium of confirming which periodic bank report to APRA is most reliable for assessing the tax, the policy makers in Canberra may yet look for clarity through simplicity.The International Monetary Fund, the originator of this tax plan, back in June 2010 defined what it labelled as a "financial services contribution" in brutally unarguable terms. In summary, this was "a levy on bank liabilities less tier one equity capital" - pretty close to Treasury's starting point.