Kenyans who fail to collect their vehicle logbooks on time will now be charged Sh500 per month, National Transport and Safety Authority Director-General Francis Meja has said.
Mr Meja said the authority is working on how the fines will be paid before being rolled out.
The fine was to be effective from mid-September.
"We do not want to receive cash," Mr Meja said, noting that the fines will be for the period the logbook will have stayed at their offices.
The agency takes five working days to process logbooks and at the moment is holding more than 15,000 uncollected documents.
Nairobi County has the highest number of uncollected logbooks at 8,763, followed by Mombasa (5,998).
Some 228 and 130 logbooks are yet to be collected in Kisumu and Nyeri respectively.
Mr Meja said some of the logbooks have been lying on the shelves for more than seven months.
"Applicants should move with speed and pick up their documents," he added.
He said the agency had made efforts to contact the individuals via SMS and through their accounts on the Transport Integrated Management System but the customers had ignored all the communication.