Revenue has introduced a temporary easing of measures for the lodging of safety and security declarations that will help business meet their customs obligations and get their goods moving between Ireland and the UK.
Britain's departure from the European Union introduces reams of paperwork and costs that must be completed to move goods across the new customs border.
For Irish firms, it means a 12-fold rise in the number of import and export declarations, the tax authority warned ahead of the changes.
Revenue said it recognised that some businesses are experiencing difficulties in lodging their safety and security ENS (Entry Summary Declarations) in respect of RoRo goods movements and also said it was aware that some trucks have been denied boarding in Holyhead.
"However, we expected challenges such as this to arise where trade and or business didn't make the necessary advance planning arrangements that we have strongly advocated over at least the last two years," Revenue said.
"We made it very clear in our engagements with industry that real, permanent and immediate changes would arise. Those who are having difficulties is the outworking of that warning," it said.
Revenue also reassured businesses that its ICT systems are fully operational and stable and working as intended and thousands of customs declarations have been processed.
Businesses who have prepared and adapted their processes in line with the new requirements have been able to move their goods to and from Great Britain with minimal delay, it added.
Revenue said the extent of the difficulties businesses are having as a result of the changes brought about by Brexit is evident from its engagement with various trade, industry and business stakeholders over the past week.
"Revenue will continue to actively work with trade and business, on both a collective and individual basis, to assist them in overcoming the challenges and issues arising," it added.
Revenue said that a new Movement Reference Number (MRN) can be used on a temporary basis if a business is unable to generate the ENS due to the absence of key information or because of other impediments that prevent you completing the process.
It said this will facilitate the completion of a company's customs formalities, the creation and population of Pre-Boarding notifications (PBN) and ultimately boarding of the ferry for movement of goods.
Take-up of this temporary facilitation will be a signal to Revenue that a company needs support. In order to avail of this support, contact ENSenquiry@revenue.ie. An expert Revenue team has been set up to provide practical guidance, to trade and business to upskill relevant staff, to ensure all businesses currently experiencing difficulties in completing a valid ENS declaration can develop the capability to lodge ENS declarations after the temporary facilitation period. This team will be in place from 8 January and will be available from 8am to 8pm.
"We expect trade and business with genuine difficulties that are impeding their ability to complete the ENS process to engage with Revenue in a cooperative endeavour to overcome their difficulties. A failure to engage may result in this temporary easement being withdrawn, so early engagement with Revenue is strongly encouraged," it added.
Please remember that the existing helpline channels remain open for queries, these are:
ENS related queries to: ENSenquiries@revenue.ie
Systems queries to: eCustoms@revenue.ie
PBN queries to: PBNqueries@revenue.ie
General Brexit queries to: brexitqueries@revenue.ie
Brexit National helpline: 01-7383685