Ugly Bob, there used to be a grace period of 14 days for road tax during which you technically committed an offence but the police would not submit a report to DVLA and/or DVLA would take no action. This is no longer the case. If you do not tax your vehicle promptly, DVLA will send you a �80 fine in the post for starters. If stopped by the police, you would most likely get a �60 fixed penalty for 'not displaying' a valid tax disc. A report would also be sent to DVLA, who can issue a court summons where you can face a large fine for driving/using/keeping an untaxed vehicle on the road.