Romney pays tax rate of "close to 15%" Mitt Romney paid taxes at a rate of "close to 15 per cent" in recent years, he said on Tuesday in an admission that will reignite debate about how investment income is favourably treated compared to ordinary wages. Mr Romney, the target of rival Republicans desperate to slow his momentum ahead of Saturday's South Carolina primary, told reporters that in the past decade his income had come "overwhelmingly from some investments made in the past." The underlying political issue is why income earned by private equity executives - the industry in which Mr Romney made his estimated $250m fortune at Bain Capital - is taxed at rates of 15 per cent, rather than higher rates paid as income tax on wages. Barack Obama, president, has insisted that the wealthy pay higher taxes to help reduce the deficit, a proposal that Republicans including Mr Romney have described as class warfare. Mr Romney's taxes moved on to centre stage on Monday evening when rival Republican candidates pressed him in a debate to release his tax returns, as they had done, something he said he would probably do in April. On Tuesday, he clarified his position, saying he wanted to wait until April to release them so he could release his most up-to-date return. "Rather than sort of have multiple releases of tax returns, we'll wait until the tax returns for the most recent year are completed, then release them," he said. The Obama administration's 2013 budget proposal, to be released in early February, is expected to reintroduce a plan to treat profits generated in partnerships such as those in private equity firms, as ordinary income. Such a change would lift the tax rate paid on private equity profits from 15 per cent to the top marginal rate of 35 per cent, and, according to White House calculations last year, reduce the deficit by $13bn over 10 years. Mr Romney's tax plan cuts capital gains tax for couples on less than $200,000 but otherwise maintains the low-tax status quo for income earned by private equity and hedge fund executives. The House of Representatives passed a bill in December 2009 ending the special tax treatment for money earned in private equity so that it would be treated as ordinary income, but the bill died in the Senate, under pressure from both Democrats and Republicans. The White House budget is likely to revive that debate and force Mr Romney to defend a tax regime which allows private equity executives to pay taxes at lower rates than many middle-income families. Mr Romney said he had also earned income from giving speeches "but not very much." The public disclosure reports filed by the former Massachusetts governor report that he made $374,327 in speaker's fees in recent years. His average fee per speech was $41,592. The median annual household income in 2010 was $49,445.