The Australian Government will make changes to tax consolidation rules introduced last year that have resulted in more than $30 billion of tax claims. But a crucial line in Assistant Treasurer Bill Shorten's statement, made on Friday, is that private rulings sought from the Australian Taxation Office will stand.Companies that have made claims under last year's rule changes include Westpac, which boosted its bottom line by almost A$2 billion after making a $685 million tax adjustment for the 2009/10 financial year and a $1.1 billion adjustment in 2010/11. Both adjustments were related to the tax consolidation treatment of its takeover of St George Bank.Amendments to the tax consolidation regime were enacted in June last year, with effect dating back to the start of the consolidation regime in July 2002. In March this year, the Government asked the Board of Taxation to review two of the amendments - rights to future income and residual tax cost-setting.The Board's review found that the revenue impact of the rights to future income and residual tax cost-setting rules has been significantly larger than expected. Claims from 2002 to the 2009/10 income year total $30.1 billion from about 60 consolidated groups.Under consolidation, a group of Australian resident entities, wholly owned by an Australian resident company, can choose to form a consolidated group. Following their choice to consolidate, the consolidated group is treated as a single entity for income tax purposes.Subsidiaries' assets are treated as assets of the head company and the tax cost of those assets is reset at an amount that reflects that group's cost of acquiring the joining entity. The re-set tax cost is intended to be used to work out the tax consequences that arise when a tax event arises for the asset. The re-set will have implications for capital gains tax, trading stock rules and capital allowance deductions. The re-set tax cost for the right to future income reflects a consolidated group's cost of acquiring that right. The intention of the rules was to set a new cost for an asset and not change to tax treatment of the asset. However, there were some anomalies in the system and last year's amendments were intended to remove them.In his statement on Friday, Assistant Treasurer Bill Shorten said: "The new laws will help protect threats to revenue by putting a limit on the scope of amendments to the consolidation regime made in 2010."So far, none of the banks have commented on the likely impact of the latest change on their tax position.