The government estimates around £110,000 is being lost in income from untaxed vehicles.
That's according to Infrastructure Minister Tim Crookall, in response to a Tynwald question for written reply from Rushen MHK Juan Watterson.
Mr Crookall says between one to two percent of vehicles currently on the roads are untaxed.
He added the Department of Infrastructure can't give an exact figure, but calculated the number based on an average tax of £165 for small passenger and goods vehicles.
Peel ready for bonfire and fireworks later
Government: "UK never told us about child murderer"
Farm shop's newest worker needs your name suggestions
Bus Vannin gives update on staffing problems and routes affected today
Toilets vandalised for fourth time in a month
Poppy gets fur-ever home after sparking rescue operation in Douglas
Council gets eight complaints about James Brown in six months
More bus staffing problems this weekend