The tax disc is going from 1 October 2014

Source: GOV.UK

From 1 October 2014, the paper tax disc will no longer need to be displayed on a vehicle. If you have a tax disc with any months left to run after this date, then it can be removed from the vehicle and destroyed. This includes customers with a Northern Ireland address, however they will still need to display their MoT disc.

https://www.gov.uk/government/news/vehicle-tax-changes