NASA has officially confirmed a December report that it had been giving Google Inc. (NASDAQ:GOOG) executives a price break on fuel for private jets. The admission came in a Feb. 24 letter to Sen. Charles Grassley, R-Iowa.

The discount, which NASA is supposed to give only to government contractors, saved H2-11 -- the private jet fleet owned by top Google executives Larry Page, Sergey Brin and Eric Schmidt -- something between $3.3 million and $5.3 million in fuel costs over five years. The discount was subsidized by taxpayers, according to NBC Bay Area.

NASA’s Seth Statler, the associate administrator for legislative and intergovernmental affairs, said NASA “reviewed its pricing approach” and “is now charging a market rate for aviation fuel.”

The tech giant was not entitled to the discount.  

In December, the NASA inspector general called the discount a “misunderstanding” rather than intentional misconduct. NASA has an agreement with H2-11 to let the Google executives to park their seven jets and two helicopters at the government-owned Moffett Federal Airfield near Google's Silicon Valley headquarters. NASA would give H2-11 discounted fuel in exchange for free flights for NASA research, but the same rate was given for fuel used to fly Google executives to Los Angeles, New York and vacation destinations like Hawaii and Tahiti.

H2-11 maintained that it paid the amount for fuel it was told to by NASA and that it pays full rate for its space at Moffett.

Grassley is pushing NASA to return the millions of dollars Google illegitimately saved back to American taxpayers, but the space agency said it’s not possible. "NASA does not have an avenue to pursue payments in excess of its full cost to provide the fuel under the earlier agreements with HS-11 as suggested by the inspector general," the agency wrote the senator.