The European Commission will present a first set of tax proposals as early as September that will, in time, allow any group of EU govern­ments to shar­e corporation taxes, according to international tax planners and consultancies in Brussels and London.

The commission's tax and customs commissioner, Laszlo Kovacs, will in September publish the tax plans for manufactured goods, de­scribed by international tax experts as "the single largest threat" to Ireland's prosper­ity, by which countries can agree to share profits under a Common Consolidated Corporate Tax Base (CCCTB).

The commission is likely to publish a second set of proposals, in December, setting out a method for countries to agree to share corporate taxes levied on the profits of financial services, according to consultants in Brussels.

Experts said the new tax proposals will be published despite comments made last week by Christine Lagarde, France's finance minister, that France will not fast track a CCCTB during its EU presidency that starts next month. Her comments were seen as a concession to Irish voters following their rejection of the Lisbon treaty.

"It remains the single largest threat to Ireland's beneficial tax regime. If CCCTB came in it would almost certainly have an adverse impact on Ireland," said Miles Walton, a tax partner at Allen & Overy in London.

"Every indication we have is that the CCCTB proposals are coming despite Lagade's comments," said Conor Foley of Hume Brophy, a Brussels-based consultancy. Foley said it was unclear why the commission wanted to publish separately a CCCTB plan for financial services but that it was likely to be designed to broaden its appeal to countries traditionally opposed to common tax plans, such as Britain.

Ireland, and other countries that want to continue with the current standalone corporation tax policies – including Poland, most Baltic states and Cyprus – oppose a CCCTB by which member states share corporate profits based on where the company is actively conducting business, rather than by the location of the registered company as is mainly used at present.

Walton said the Irish No vote may slow the process toward the adoption of CCCTB but he thought it would eventually be adopted. "I can see why the Irish will be implac­ably opposed, forever... The EU will have to get the approval of Britain and have some alternative propos­als that will be acceptable," he said.