The director of Dialogue Direct Fundraising UK, the agency that went into voluntary liquidation last week, said that the organisation did not owe any money to charities.
Andreas Leitner said there would be "no negative fallout for charities" and that outstanding bills had been paid.
Dialogue Direct ceased trading after HM Revenue & Customs, a major creditor, failed to agree a new payment plan.
The Oxford-based company, which signed up a total of about 80,000 donors a year, employed about 20 office staff and 35 teams of five or six people.
It worked with several major charities, including the RSPCA, Save the Children and the British Red Cross.
Alice Montague, direct marketing manager at the British Red Cross, said it had "measures in place to ensure the closure of the company does not directly affect our fundraising targets".
The RSPCA confirmed it was not owed money.