The Restaurants Association of Ireland (RAI) is calling for a reversal of the hospitality VAT increase ahead of any no-deal Brexit.
It is calling on the Government to provide "stability and reassurance" to the tourism and hospitality sector, by reducing the 13.5% VAT rate back to 9%.
The VAT rate was reduced in 2011 from 13.5% to 9% to help encourage and support the growth of small businesses.
It was due to expire in 2013, but successive Governments kept it in place until Budget 2019.
It is thought the increase will generate an additional €466m in VAT receipts for the exchequer in 2019.
It is mainly impacting hotels, other short-term guest accommodation providers and restaurants.
But it is also applied to things like coffee shops, cinemas, theatres, hairdressers, museums and art galleries.
Adrian Cummins, chief executive of the RAI, said: "Given the increasing potential of a no-deal Brexit, and the major implications that would have for Irish small and medium businesses, the RAI are calling on the Government to bring the VAT rate back to 9% ahead of March 29th".
If a no-deal Brexit happens, the RAI has said many small Irish businesses will become EU importers.
"It may cause serious issues in supply chains and also narrow the market for the tourism and hospitality industry", it added.
The UK accounts for over one-quarter of all overseas tourism revenue, and almost half of all overseas visitors to Ireland.
The RAI has said raising the VAT rate to 13.5% has "undermined the competitiveness and viability of Irish businesses".