Having a leisure vehicle that isn't used for the whole year but potentially used for longer than 6 months, I think it would be easier to tax it for 3, 6, 9 or 12 months. Rather than just 6 or 12, where the Autumn and Winter months the vehicle may be just sitting in the garage.
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I think it's time that motor vehicle road tax duration is changed
As a fair weather motorcyclist I have found that if I tax my vehicle for 12 months my motorbike sits in my garage for at least 4 months unused through the winter. Taxing the vehicle for 6 months say from April to September some times isn't long enough if the weather's nice in the October.
I think it's time that you should be able to tax it for 3/6/9/12 months
I think it would suit more leisure vehicle owners to tax their vehicle for 9 months.