The European Commission has cleared the final transfers of €47bn of loans to Nama from the main banks.
Nama paid the banks €18.995bn for the loans - a discount of around 60pc compared to the face value.
However, the Commission's report said the market value of the loans was €15.681bn.
The Commission calculated that the value of the properties underlying the loans was €19.6bn.
The additional €3.2bn paid to the banks is regarded as potentially problematic state aid, which was why EU approval was needed for the loan transfers.
Officials in Brussels approved the establishment of Nama and cleared the initial two tranches of loan transfers back in 2010.
The head of Nama, Brendan McDonagh, said that the Commission's approval confirmed the robustness of NAMA's due diligence. He added that this means that NAMA applied the correct valuation to the loans it acquired.
"We adopted a prudent, consistent and fair valuation policy in respect of these loans and the valuation process was fully in accordance with the Commission's requirements," Mr McDonagh said.
According to the Commission the loss of €28bn suffered by the banks when the loans transferred are in line with its principle of "burden sharing" which is based on lenders taking a hit for bad lending, even when the State steps in.
However, in the case of the Nama transfers the bulk of the losses fell on State-owned banks and ultimately on taxpayers.
Of the €47bn of loans included in the final transfer Anglo Irish Bank was the biggest single source (38.9pc), followed by AIB (30.6pc), Bank of Ireland (13pc), Irish National Building Society (15.9pc) and EBS (1.5pc).
Irish authorities notified the EU of the transfer earlier this year, and discussions on the process, including in relation to valuations, took place between April and July.
Since the start of this year Nama has speeded up the sell-off of loans originally received from the bank, especially Irish loans.
Earlier this month Facebook's plush Dublin headquarters was put on the market as part of Nama's declared strategy to sell at least €250m worth of assets every three months as it reduces its property portfolio and takes advantage of the recovering commercial property market.
Facebook moved into the building in the capital earlier this year.
The fact that the property now has a top-level tenant with global recognition is likely to help attract a range of international buyers.
Indeed Facebook itself may bid for the office. The company is not affected by the sale.