The Commerce Ministry should have taken into account rice in its stockpiles when calculating losses from the pledging scheme, said Assoc Prof Somporn Isvilanonda, a senior fellow at the Knowledge Network Institute of Thailand.
The government loses 8,277 baht for every tonne of rice bought under the subsidy programme.
He estimates the government bought 23.49 million tonnes in the previous three crops, so losses could be 194 billion baht on top of the management fee of the programme at 20 billion baht a year.
The Commerce Ministry has garnered only about 40 billion baht from selling 3,000 tonnes of rice to the Philippines, 97 tonnes to Bangladesh and 3 million tonnes domestically, he said.
Separately, Korbsook Iamsuri, president of the Thai Rice Exporters Association, said although the Finance and Commerce ministries used different accounting methods in calculating the figures, it should be noted that rice is perishable.
"No matter what method is used, we should not forget that rice is not like gold, which can be kept forever with the quality intact while we wait for the price to increase," she said.
"It's true rice prices may rise one day, but there will always be a depreciation cost due to deteriorating quality. In general accounting practice, they tend to base the calculation on mark-to-market prices to evaluate the performance."