New controls on imports entering Britain from the Republic of Ireland have come into effect.
The changes, which are a result of Brexit, require firms to pre-lodge customs declarations ahead of shipping products across the Irish Sea.
Agri-food exports also have to be pre-notified to the UK authorities and in some cases they have to be accompanied by an Export Health Certificate.
The additional requirements come on top of formalities already in place for goods that are being exported to the EU.
Loads which have not had the required documentation properly completed and filed at least 24 hours in advance will not be allowed to board ferries leaving Ireland for the UK.
But while authorities had been concerned about the preparedness of smaller Irish businesses for the changes, major disruption at ports is not currently anticipated.
Physical checks of goods entering Britain from Ireland will not be introduced until later in the year.
The UK remains Ireland’s most important trading partner with over one third of Irish exports going there. In 2022 Irish food and drink exports to the UK were worth €5.5 billion.
The controls were supposed to be put in place a number of times over recent years, but were repeatedly delayed because UK agencies were not ready.
Campaigns have been run by Irish and British government agencies to bring Irish exporters, logistics providers, ferry operators and others up to speed since the plans to commence the controls were announced last August.
The requirements do not apply to goods that are moving from Ireland to Northern Ireland, while qualifying goods originating in Northern Ireland will continue to have unfettered access to Britain.
The rules do apply though both to goods transported directly from Ireland to Britain or indirectly via Northern Ireland to Britain.