The Driver and Vehicle Agency (DVA) has apologised for a blunder which meant some customers could have paid the wrong level of duty.
Rates of duty changed on April 1, 2011 after the Chancellor’s Budget in March but some of the reminders issued in May showed the old rates.
The agency blamed “timing” issues for the error and has issued new reminder notices.
A spokesman for the DVA said: “We apologise to all of the customers affected, and for any inconvenience they experience as a result.
The agency said that the correct rate of duty must be paid regardless of the amount displayed on the reminder notice.