Chief executive Lin Homer also denied that the tax firm her predecessor joined after his retirement had played any significant role in major tax deals struck with private companies.
Dave Hartnett, the former head of HMRC who was criticised for "sweetheart deals" with big firms, became a consultant to Deloitte in May. The former permanent secretary was appointed to advise on foreign governments and tax administrations less than a year after retiring from his taxpayer funded role.
MPs criticised Mr Hartnett in 2011 for striking ''cosy deals'' with some big companies over their tax bills, letting corporations off paying large sums of money.
Margaret Hodge, who chairs the Public Accounts Committee, said there was a suggestion that Deloitte had been the "preferred facilitator" when deals were struck.
Ms Homer rejected the claim, telling the PAC: "Not to my knowledge and I don't see any evidence to suggest that they were playing either a preferred or significant role in our large disputes."
"What's really of interest is those occasions when you were buying advice from a firm such as Deloitte and the same firm was also selling its advice to a large taxpayer such as, to take one example, Vodafone."
He added: "If you were turning out to be the marriage broker who introduced the adviser to the company....."
Ms Homer replied: "That is an assertion that I do not accept, Mr Bacon. You have made that assertion, I have no evidence to support that. I'm not prepared to have it said..."