The bad bank has stopped selling mortgages and simply collects and services outstanding loans.
UKFI also claimed that its analysis showed that the sale of Northern Rock to Virgin Money had been the best result for the taxpayer.
It said Deutsche Bank, which had been brought in as its adviser on the sale, had put an estimate on the proceeds of between £863 million and £977 million.
This compared with Deutsche's estimates of the proceeds for the taxpayer from an initial public offering from £270 million to £495 million, a remutualisation worth upwards of £415 million or a sale of Northern Rock's deposits and run-off of its loans which could have made from £561 million to £625 million.
UKFI also said holding on to Northern Rock until 2013 (when it had to be sold under EU state bailout rules) would not greatly have added to its valuation, which even then would have been a quarter less than Virgin paid.
It said that while there had been some political support for remutualising Northern Rock, it would have been the least productive outcome for the taxpayer. Treasury would have had to give free shares to the bank's customers as they converted into members of the mutual.
The sale to Virgin was also the most attractive outcome in terms of new competition in the UK banking sector, said UKFI.
- Independent