Onwards of January 1, 2020, the Roads and Transport Authority of Dubai has made it mandatory for all motorists to upgrade to the new plate design. The authority has notified that the change of number plate for new registrations will start from January 1, 2019.
As of January 1, 2020 it is mandatory for all personal vehicles to get the new designed license plates. As for vehicles owned by private and public sectors, their license plates can be changed starting July 2019. pic.twitter.com/Rd0i1922vS
— RTA (@RTA_Dubai) December 20, 2018

The authority has notified that the change of number plate for new registrations will start from January 1, 2019
Apart from that, the upgrade for vehicles registered in the name of private companies and government departments will begin from July 2019. Earlier reports suggest that the new rule, that was initiated through a campaign conducted by the RTA, was brought about to implement a new strategy for number plate that would result in new generation plates with double codes.
“The RTA has developed a new strategy for number plates resulting in a new generation of number plates with double codes. This has accordingly resulted in the number plates to be changed to adopt the single and double codes with the same design language.” director of RTA’s Vehicle Licensing, Sultan Al Marzouqi told Gulfnews.

Earlier reports suggest that the new rule, that was initiated through a campaign conducted by the RTA, was brought about to implement a new strategy for number plate that would result in new generation plates with double codes
How To Change Your Number Plate
Log on traffic.rta.ae and follow the steps below:
1) Keep your vehicle details including your plate details ready as you will need them.
2) Select your style from the options.
3) You also have an option to add the coloured Dubai logo for an extra cost.
4) Once the style and other additions have been made, you can then select your preferred RTA centre from the list at which you can go and exchange your current number plate for a new one.
5) Payment can be made directly, depending on the shape and the colour you have chosen.
(Image Source: Gulfnews.com)