The Federal Government is on track to collect A$1.55 billion in the current financial year through its controversial wholesale funding levy, but the net additional tax take from the four major banks and Macquarie will be substantially less than expected.Disclosures made by Westpac on Monday indicate that it will likely absorb the biggest hit from the levy, after it incurred a $95 million bill in the September quarter.Based on this disclosure, Westpac is facing $380 million in estimated levy costs for the 12 months to the end of June.That is slightly more than National Australia Bank, which is in line to pay out $376 million, after it incurred a $94 million levy liability in the last quarter.CBA estimates its gross levy charges will total $369 million, while ANZ is staring at a $350 million payment after it incurred a liability of $86 million in the three months to the end of September.Macquarie Bank told a recent parliamentary hearing that it expects the levy will augment its full year tax costs by around $70 million.However, there's a chance the total levy proceeds received by the government could rise this year as several of the major banks mount large wholesale funding programs to support current and future lending.That prospect, spurred partly by a slowdown in retail and business deposits growth, could magnify the reliance of the majors on wholesale funds.As the banks increase their reliance on wholesale funding their levy-related liabilities will also increase.Westpac chief financial officer Peter King yesterday signalled that his bank was eyeing more offshore funding this financial year to replace programs that were nearing maturity."Wholesale funding costs were lower as we replaced maturing deals at lower costs and we saw good demand for our paper this period and our SEC registration was particularly helpful in our hybrid transaction," he told analysts on Monday."The funding markets are looking the best they've been in some time."While the federal government can count on the levy hauling in more than $1.55 billion in new revenue, the net tax boost from the banks  - on current trends - will be significantly less.That's because the levy is reducing - dollar for dollar - the taxable income of the banks.Commonwealth Bank estimates that the net impact of the levy on the group's 2018 total tax bill will be $258 million, which is $111 million or 30 per cent less than its expected levy liabilities.We can extrapolate from that disclosure that around $465 million of the $1.55 billion the government stands to collect under the levy would have otherwise been received through corporate income tax.This means that the net tax benefit of the wholesale funding levy to the government's coffers for the 2017/18 fiscal year is likely to be around $1.1 billion.Although the banks are accounting for the costs of the levy as they accrue, they do not have to begin remitting tax payments to the government until March next year.