You can pay your car tax online if:
During the online application your insurance, MOT and any entitlement to a disability exemption will be checked.
A receipt for your payment and a tax disc and will be mailed to you within 5 working days.
Your insurance, on the start date of the tax disc or the date you apply later, is checked on the MID (Motor Insurance Database). If your car tax and insurance are due on the same date or if you have recently changed your insurance company, there could be a problem with checking your insurance details as the MID may be updating their database. Before you can check online to see if the MID has updated.
Make sure to have the following when you Pay Your Car Tax Online