The Restaurants Association says a quarter of businesses won't reopen for indoor service tomorrow.
The final regulations to allow indoor service are expected to be signed off today by government.
Some publicans and restaurateurs say regulations governing indoor hospitality are "unworkable".
Only fully vaccinated people, or those who have recovered from Covid-19, will be allowed inside a pub or restaurant, and they'll have to provide proof of immunity.
Photo identification will also be required and all customers will have to give details for contact tracing.
Philip Foster, owner of The Snail Box restaurant and pub in Ashbourne, Co. Meath, won't be providing indoor service - he says the rules will be too difficult to implement:
"The staff isn't trained to read certs [...] if we don't read them right then there's trouble. How do you police it I think it's very hard? You need extra staff which we wouldn't have anyway, our key personnel would then be on doors."
Some publicans and restaurateurs say they're concerned about possible backlash from the public when indoor hospitality re-opens tomorrow.
Padraig Cribben from the Vintners' Federation is appealing to the public to follow the rules tomorrow:
"Publicans over many years have been used to dealing with, lets call them tricky situations, but we would ask the public to make life as easy as possible for those trying to get back in business again."