Tui Travel yesterday admitted it had found a £117m hole on its balance sheet, a blunder that will see the finance director depart the company.
The holiday operator – which owns the Thomson brand – was forced to restate its financial results for errors that go back several years.
Paul Bowtell has offered his resignation and will leave by the end of the year.
TUI says the write-offs are the result of “failures to reconcile balances adequately in legacy systems”.
After the merger with First Choice in 2007, the company used two separate computer systems, one to make bookings for customers, the other to process data from tour operators. Discrepancies arose when discounts offered to customers were not recorded on the tour operator system.
Chief executive Peter Long, an industry veteran with decades of experience, said the computers were in error.
He said: “It is now clear that at the time of the merger there were weaknesses in the legacy systems we chose to use in the Tui UK business.”
Long added: “Despite the fact that this situation had built up over a number of years, Paul is behaving honourably and I am disappointed that he will be leaving the group.”