HM Revenue and Customs has faced criticism from MPs over alleged secret deals with the likes of Vodafone and Goldman Sachs over unpaid tax.
However, John Cridland, director-general of the CBI, said: "I spend my working day talking to companies across the country.
"Frankly I don't recognise the notion that Her Majesty's Revenue & Customs is a soft touch. Far from it: Tough, but fair. Reports about so-called 'sweetheart deals' between business and HMRC are wide of the mark.
"The 'tax gap' between what should be collected and what actually is has been shrinking in recent years.
"Only £1.2 billion of the total £35bn is attributable to corporation tax paid by the largest companies."
The controversy over the deals is set to continue because HMRC faces a legal hearing on the Goldman Sachs case June following court filings made by activist group UK Uncut Legal Action.
Mr Cridland said: "Businesses are increasingly aware of the reputational risks associated with abusive arrangements and 'black-box' schemes.
"Business pays the tax it's required to – and we're talking about a huge amount of money, in both cash terms and as a proportion of total government revenue."