The Office of the Auditor General has demanded the government take responsibility for the 3.8 billion baht spent on the now nullified Feb 2 election.
The office on Wednesday wrote to former prime minister Yingluck Shinawatra, demanding her government foot the bill.
It claimed it had warned her government that the spending would be a waste.
The office had said the polls were unlikely to succeed amid the turmoil and could be nullified.
It referred to the attempts of anti-government protesters to disrupt the Feb 2 election because they wanted political reform before the election.
The protesters managed to block candidacy registration in some constituencies and elections at some polling stations.
The Constitutional Court ruled in March that the Feb 2 election was unconstitutional as it did not happen nationwide on the same date as required by the constitution.
The office also stated on Wednesday that the government and responsible authorities had to take care to avoid such a waste in the future.