Students from Northern Ireland and Britain will face the same higher education fees as EU students on an ongoing basis in the event of a hard Brexit.
While the Government has previously pledged to freeze fees for UK students starting undergraduate courses in 2019 only, an amendment to the Brexit Omnibus Bill would maintain this system indefinitely.
The bill, passed by the Dáil on Wednesday, is emergency legislation which would only be triggered in the event of a no-deal Brexit.
About 1,200 students from the North currently attend colleges in the Republic, while more than 2,000 students from the Republic attend colleges in Northern Ireland.
Fianna Fáil education spokesman Thomas Byrne, who proposed the amendment, said it would protect the flow of students between Northern Ireland and the Republic.
“Having spoken with many families who have contacted me and our partners in the SDLP, it was evident that guarantees were required for students from Northern Ireland beyond 2020. This was a change I have been calling for since 2017,” Mr Byrne said.
“Maintaining the flow and mobility of students between north and south is essential.”
Mr Byrne said he hoped UK authorities would reciprocate the arrangement for Irish students studying in Britain and Northern Ireland.
UK ministers have pledged to maintain existing fee structures for Irish students wishing to pursue higher education courses in the UK in the 2019/2020 academic year. They have yet to offer guarantees beyond this date.
Fees for Irish students studying in the UK vary at present, but are typically up to £4,275 (€4,762) in the North and £9,250 (€10,300) in England.
If Irish students were treated as international students post-Brexit, there have been fears that these fees could jump up to £35,000 (€38,990).
Similarly, UK students who enrol for eligible courses in the Republic are charged on the same basis as EU students and face a €3,000 registration charge.
This regime will continue on an ongoing basis in the event of a hard Brexit following amendments to the Brexit Omnibus Bill .