The figure, which takes into account the cost of borrowing money to fund the £20 billion bail-out in 2009, appears to undermine a claim by Chancellor George Osborne that the share sale in September represented "a profit for taxpayers".
It would suggest that the overall loss on the £20bn bailout could be nearly £1.5bn if the rest of the stake is sold off at a similar price - though the NAO did not make such a calculation.
Mr Osborne trumpeted in the autumn that the £6.2bn Lloyds share sale had resulted in the national debt being reduced by more than half a billion pounds. This £586m figure represented the difference between the value for accounting purposes of the shares on the Treasury's books - at 61p - and the 75p sale price. The Treasury acknowledged at the time of the sell-off that the cash profit was far less, at £61m.
The report by the watchdog does not dispute the calculations but does take into account the effective interest paid to make the original investments in the bail-out. It recommends the Treasury should consider these costs when analysing the value of any future sale.
The report said the average rate paid for shares by the Government of 73.6p was effectively cut to 72.2p by the fact it had been paid back some of the money by Lloyds in fees -producing a cash profit of just under £120m. But it says that if the cost of financing is taken into account, the sale resulted in a shortfall of £230m.
UK Financial Investments, which manages the Government's stakes in the bailed-out banks, ran the sale in a process which the NAO said was "managed effectively and provided value for money".