The county council told The Standard the reason for its delay in providing the information to the Boston Bypass and Economic Growth Pressure Group (BBEPG) was because council resources were diverted into looking at a Lincoln bypass.
Robert Fisher, chairman of BBEPG, wrote to the council on September 6 asking for the total cost of the Boston Transport Study.
BBEPG has received a letter admitting the council's error in relation to the 2000 Act.
The Act states the council must reply to requests for information within 20 working days unless additional time is required relating to exempt information.
On October 3 the group received an email from the council's information compliance officer, stating: "I write to inform you I have been notified by the Technical Services Partnership (the department handling your request) that unfortunately the information will not be ready to be sent today.
"You will be aware this puts us in breach of the legislation under the terms of the Freedom of Information Act 2000, which states we must reply within 20 working days.
"Unfortunately I have not been provided with an explanation for the delay from the partnership, nor have I been provided with an estimate of when the information will be ready."
Yim Kong, head of technical services at LCC, told The Standard on Monday: "Yes, we have been late in complying with the act and it is not something we condone.
"BBEPG should have its information by the end of the week at the latest.
"The reason we were delayed is because our staff have been diverted into looking at the major consultation exercise with the Lincoln Southern Bypass.
"I apologise to BBEPG, but this is the first time such a delay has ever happened – despite us fielding numerous requests under the Act since it came into effect."