Statistics for 21 of Scotland's 32 council areas were obtained under freedom of information laws by the Scottish Conservatives.
They reveal big differences across Scotland in how long it takes local authorities to pay their bills, with one council paying just 10% on time, the party said.
Scottish Government targets are for payment within 10 working days, said the Conservatives, who branded councils' payment rate disappointingly poor.
The statistics for 2012/13 showed Edinburgh City Council paid 70% of invoices in time while Renfrewshire, Highland and East Renfrewshire managed 67%, 66% and 64% respectively.
However, East Ayrshire paid only one in 10 invoices within the target timeframe, South Ayrshire managed 18% and Aberdeenshire 20%.
Tory MSP Margaret Mitchell said: "Councils should be leading by example by settling invoices promptly, not hanging on to money for weeks on end."