Farmers who move goods in and out of Northern Ireland from Britain or bring goods into NI from outside the UK have been told to sign up to the Trader Support Service.
The free government service will guide farming businesses through post-transition period changes.
It will also provide them with a business registration number needed to transport goods from 1 January 2021 with the implementation of the NI Protocol.
Goods can include something as simple as ordering a second-hand tractor part from England or buying a bull from Scotland, purchases that can be very regular for some farmers.
If registration is done before 23 November 2020, this will be an automatic process but if this is done later, a separate application will be required.
The Ulster Farmers’ Union (UFU) has urged farming businesses in the region to 'act now' and apply to the Trader Support Service, or risk 'serious issues' in the future.
UFU president Victor Chestnutt said: “It is essential that our members who transport goods across the water or do so on another’s behalf, sign up for the free TSS.
"It will provide them with a necessary business registration number needed to transport goods, will explain all the changes that come into effect with the implementation of the NI Protocol and the service can complete declarations on your behalf.
"I urge our farmers to act now to give themselves time to prepare and get their farm businesses ready for the inevitable changes that lie ahead.
"If they fail to sign up to the TSS, this could cause serious issues for the daily running of their business as they may not be able to move essential goods into NI.”
The government has pledged to spend £200m over the next two years on the Trader Support Service.