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.
Tin bath races mean bus diversions tomorrow
MHK wants backing for changes to Tynwald members' pay
Storage firm announces closure
Mountain Road shut for skate setup later
Bus diversions for tin bath day tomorrow
MP criticises Island's fishing visa rules in Westminster
Post Office won't release Evri documents as courier prepares to leave Island
Strix to shut Ramsey factory