The impact of non-tariff barriers to trade, such as technical standards or health regulations, could reduce trade between the United Kingdom and Ireland by up to 10% after Brexit, according to new research by Central Bank economists.
The economists say "red tape" could increase delays by up to four-and-a-half hours at the UK borders with Ireland, particularly at sea ports.
The researchers have tried to calculate the impact of the extra red tape that would apply if Britain leaves the customs union.
A delay of that length could see a fall in goods trade between Ireland and Britain of up to 9.6%, which equates to a 1.4% fall in total Irish exports, and a 3% fall in total imports.
However, the impact would not apply equally to all goods exports and imports.
Agriculture, machinery and transport would be the most heavily affected sectors of the economy, but trade in chemicals, fuels and imperishable foods would hardly be affected, which are a substantial part of UK-Irish trade.
The results do not take account of any special relationship that may be negotiated between the UK and the EU.
The report says that Norway and Switzerland currently have lower border waiting times than the UK, despite the fact that neither country is a member of the EU.
The authors note that even if companies can get an exemption from tariffs and duties on materials that are imported then re-exported after processing, there is no exemption from non-tariff barriers.
They warn that fresh foods may face much longer waiting times than their model suggests, which would then underestimate the trade impact on that sector.
Data from Irish customs officials indicated that agricultural goods from non-EU countries currently face waiting times of between 83 minutes and 19-and-a-half hours at ports where physical inspection is required.