The hospitality sector is seeking assurances from Stormont that it can reopen on December 11.
The hospitality sector, along with non-essential retail and close contact services, will close for two weeks from Friday November 27 as part of circuit-break restrictions to stem the spread of the coronavirus before Christmas.
The measures were announced by Stormont last week after warnings the health service could become overwhelmed if action was not taken.
Hospitality Ulster chief executive Colin Neill said he is writing to First Minister Arlene Foster and Deputy First Minister Michelle O'Neill to ask for clarity to allow businesses to plan.
"This is an extremely important part of the year for a number of reasons, but even more so this year as business owners fight to save jobs and their businesses, and reduce their crippling losses in the very short pre-Christmas trading period if it comes," he said.
"The hospitality sector has suffered immensely this year, and the opportunity to be open and doing what they do best over Christmas would bring both a much needed morale boost and ease some of the financial pressures."
Mr Neill added: "If the Executive decides to make the unfortunate call to continue with the lockdown over (the) Christmas period they must make this decision now instead of the eleventh hour.
"We've been in situations in the last few months when decisions have been made way too late which causes huge confusion and additional financial losses within the sector. This simply cannot happen again."
Ms Foster and Ms O'Neill announced yesterday, as part of a plan agreed across the UK, that people from three households will be allowed to meet indoors for five days over the Christmas period.
Dr Tom Black, chairman of the British Medical Association's Northern Ireland Council, urged the "matriarchs of Northern Ireland" to ensure families remember social distancing if they mix over Christmas.
"It'll be women that will be deciding this and they know that 18 to 20 people in a room hugging is a bad idea," he told the BBC.
"But they also know if they can push it to eight or ten - or maybe 12 if that brings in granny - and we try not to hug granny and we try and maintain distance as best we can and maybe do a buffet instead of passing dishes around a table, that is a way to limit the risk in this."
The Executive is set to meet tomorrow to discuss arrangements for Christmas further.
