The head of HM Revenue and Customs has denied the organisation acted as a "marriage broker" that introduced tax advisers to private companies.
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."
Conservative MP Richard Bacon quizzed Ms Homer on how many times advisers had been present at meetings.
"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..."
10 of the biggest consumer rip-offs
HMRC chief rejects tax deal claims
Using a mobile phone to make and receive calls, send texts and browse the web while abroad can be extremely costly – especially if you are travelling outside the European Union (EU), where calls can cost up to 10 times as much as at home.
To avoid high charges, Carphone Warehouse suggests tourists ensure a data cap is in place, use applications to check data usage, turn off 'data roaming', avoid data-intensive applications such as Google Maps and YouTube and use wi-fi spots to update social networking sites.
Payment Protection Insurance (PPI) is supposed to help people to continue meeting their loan, mortgage or credit card repayments if they fall ill or lose their jobs. However, policies are often over-priced, riddled with exclusions and sold to people who could not make a claim if they needed to.
At one point, sale of this cover - which was often included automatically in loan repayments - was estimated to boost the banks' profits by up to £5 billion a year.
Now, though, consumers who were mis-sold PPI can fight back by complaining to the bank or lender concerned and taking their case to the Financial Ombudsman Service (08000 234567) should the response prove unsatisfactory.
It could be you, but let's face it, it probably won't be. In fact, buying a ticket for the Lotto only gives you a 1 in 13.9 million chance of winning the jackpot.
With odds like that, you would almost certainly be better off hanging on to your cash and saving it in a high-interest account.
No-frills airlines such as EasyJet may promote rock-bottom prices on their websites. But the overall fare you pay can be surprisingly high once extras such as luggage and credit card payment fees have been added - a process known as drip pricing.
Taking one piece of hold baggage on a return EasyJet flight, for example, adds close to £20 to the cost of your flight, while paying by credit card increases the price by a further £10.
It may therefore be worth comparing the total cost with that of a flight with a standard airline such as British Airways.
Cash advances, which include cash withdrawals, are generally charged at a much higher rate of interest than standard purchases.
While the average credit card interest rate is around 17%, a typical cash withdrawal of £500, for example, is charged at more than 26%.
What's more, as the interest accrues from the date of the transaction, rather than the next payment date, costs will mount up even if you clear your balance in full with your next payment.
Supermarkets such as Tesco and Asda often run promotions under which you can, for example, get three products for the price of two.
However, it is only worth taking advantage of these deals if you will actually use the products. Otherwise, you are simply buying for the sake of it, which is a waste of your hard-earned cash.
Buy a train ticket at the station on the day of travel and the price is likely to give you a shock - especially if you are travelling a long distance at a busy time of day.
However, you can cut the cost of train travel by 50% or more by going online and making the purchase beforehand - especially if you book 12 weeks in advance, which is when the cheapest tickets are on sale.
Other ways to reduce the price you pay include avoiding peak times and taking advantage of so-called carnet tickets, which allow you to buy, for example, 12 journeys for the price of 10.
Most High Street banks offer packaged accounts that come with monthly fees ranging from £6.50 up to as much as £40, with a typical account charging about £15 per month.
Various benefits, such as travel insurance and mobile phone insurance, are offered in return for this fee. But whether or not it is worth paying for them depends on your individual circumstances.