It is the "last call" for motorists living in Ireland but using a UK driving licence to have them exchanged before Brexit.
Almost 55,000 licences have been exchanged so far this year ahead of the deadline on December 31st.
However, it is estimated that around 15,000 motorists living in the Republic and still using a UK driving licence face being put off the road within weeks as the Brexit transition deadline looms.
Brian Farrell, Communications Manager at the RSA, said people need to get their house in order.
He told The Pat Kenny Show: "People by the end of this year will have had two years to get their house in order.
"It's really the last call for anyone who is resident in Ireland and holds a UK or Northern Ireland licence to get them exchanged before the transition period expires on December 31st.
"And if they don't they face the reality of that licence becoming invalid because what happens is the UK becomes what we call a third country, it has the same status as someone from Amerca whos over here.
He added that the requirement for licences to be exchanged is for residents only and does not apply to tourists.
He said: "If you are someone on a temporary visit here with a UK licence, if you're a tourist, you won't be affected, it's only if you're resident here."
Mr Farrell added that the Government is working to find an agreement with the UK for after December 31st but there is uncertainty over how long this will take.
He said: "The reality is that when January 1st comes along, if you haven't exchanged your licence, you're licence is invalid and you cant use it to drive in this country.
"You need to exchange your licence while the mechanism that allows you to exchange it under European regulations still exists.
"To date this year, we have exchanged almost 55,000 UK and Northern Ireland licences, so the vast majority of people are heeding the messages.
"We estimate that there could be anything up to 15,000 further licences out there to exchange."
Mr Farrell said that if people who are resident in the UK or Northern Ireland travelling here for the purposes of work in Ireland, their licence is fine.
