The Irish government's no-deal contingency document, published last month, refrained from stating what might happen at the border in a no-deal scenario.
Tariffs would still apply to 13% of goods imported into the UK.
The Irish PM said the most pressing issue facing his country was how to settle questions about the future of the border between Ireland, an European Union member, and Northern Ireland, which won't be.
Ministers said today that products from the European Union including beef, pork, chicken, butter, cheese and fish would also be subject to import taxes expected to push up prices in the supermarkets from March 29 if there is no deal.
The UK Government will slash import tariffs to zero across 87% of goods in the event of a no deal Brexit to try avoid higher prices for consumers - but the cost of food and cars is set to rise, according to plans revealed this morning. Unfortunately rather than accept defeat, May refused to back down and recognize the will of Parliament and instead responded by saying a no-deal Brexit is still the default unless a deal is made.
The government said it would not apply a tariff regime and customs border on goods transiting across the land border from Ireland to Northern Ireland but admitted that this created a "potential for exploitation" if those goods are then transported across the sea to mainland Britain for sale.
To protect human, animal and plant health, animals and animal products from outside the European Union would be required to enter Northern Ireland through a designated entry point, while regulated plant materials from outside the European Union and high-risk plants from inside Europe will require certification and pre-notification.
No deal Brexit: No tariffs for Irish goods going to NI
Imports such as beef, "cheddar-like" cheese and butter would be subject to tariffs as a percentage of the EU's "most favoured nation" level - a World Trade Organisation measure.
The government said it recognises that Northern Ireland's businesses and farmers will have concerns about the impact that the government's approach will have on their competitiveness.
MPs rejected the EU Withdrawal Agreement by an overwhelming majority - 391 voted against the deal compared to 242 in favour.
The government said: "British businesses would not pay customs duties on the majority of goods when importing into the United Kingdom if we leave the European Union without an agreement".
Goods crossing the border from Ireland into Northern Ireland would not be covered by the new import tariff regime.
In the case of no-deal, the UK Government is committed to entering discussions urgently with Brussels and Dublin to agree long-term arrangements.
"But we will do all we can to support people and businesses across Northern Ireland in the event that we leave without a deal". These arrangements can only be temporary and short-term.