British companies could see their pension costs increase by £10 billion a year under accounting changes expected to be proposed this month by international standard setters, according to accountants PricewaterhouseCoopers.

The International Accounting Standards Board has promised to publish an exposure draft in the first quarter of 2010 setting out how it plans to revise the pension accounting standard, IAS 19.

The PwC figure is based on the firm’s expectation that IASB will propose companies should no longer be able to treat a return on pension scheme assets as a gain in their profit and loss account.

That would mean most companies would have to report higher pensions costs. A company with a £2 billion pension scheme would typically see reported pension costs rise by about £25 million a year, PwC said.

However, the firm said it was supportive of the improved transparency on pensions disclosure that the changes would bring.

“The proposals would radically change the way organizations are required to account for their pension costs,” said PwC partner Brian Peters. “We are likely to see resistance to the accounting changes from companies in both the UK and rest of Europe. Nonetheless, those changes designed to provide transparency and consistency are to be welcomed.”