A Cornwall Council committee is expected to review why financial information sent to a national newspaper was incorrect.
Information sent to the Daily Telegraph over the use of payment cards included statistics using incorrect currencies.
The council told the newspaper it had spent nearly £9m on cards since 2008, but later found that, because of mistakes, it was "at least" £1.3m less.
Councillors expect the results of the review by the end of the month.
The payment cards are used to pay for things direct from a council account, rather than on credit.
Some 509 payment cards are in use by the council. Of those, 154 were allocated to schools, the authority said.
The figures, given to the newspaper following a Freedom of Information request, were published on Saturday.
Among the figures sent to the newspaper was £114,142 for hotels in India, which was actually in rupees, and should have been £1,645.
The council, which is controlled by the Conservatives and Independents, is now checking all the figures.