US trade tariffs

No. The Windsor Framework does not apply to exports from Northern Ireland to the US. It is a trade arrangement specifically governing the movement of goods between Great Britain, Northern Ireland, and the European Union. 

Exports to the US from Northern Ireland are subject to standard export and import procedures.

The Most Favoured Nation (MFN) principle is one of the key foundations of the global trading system. It prevents discrimination against different trading partners. 

MFN tariffs are set by each country for each product in the Harmonised System (HS) classification. In the absence of any trade agreement, the tariffs are the base rate of customs duties applicable to imports from other countries. They are the third-party tariff that countries charge for imports.

The US has MFN tariffs in place and these are charged alongside all the applicable new tariffs recently announced. 

The UK does not have a free trade agreement with the US. No preferential tariff rates are available.

Yes, additional tariffs are applied on top of the MFN rates.

This can be challenging due to frequent changes in tariff policies.

The UK tariff tool allows you to look up tariffs for goods exported from Northern Ireland to trading partners, including the new US tariffs. You should note for exports, goods shipped from Northern Ireland to third countries (i.e. countries outside Great Britain and the EU) are treated as exports from the UK.

While this tool provides a useful indication of current US tariffs, it is not legally binding. For official tariff rates and legal certainty, you should consult the relevant Proclamations and official US government guidance.

Access the UK tariff tool and select the export tab.

Alternatively, you can check how to export goods.

The importer is responsible for paying the tariffs i.e., the entity listed on the customs declaration at the time of import. However, this responsibility depends on the Incoterms agreed upon by the seller and buyer. Incoterms define which entity—whether in the exporting country or the importing country—handles export and import formalities, including tariff payments.

Please note that this designation refers specifically to the party responsible for paying tariffs to customs authorities. However, the importer and exporter may mutually agree to share these costs or for the importer to assume full financial responsibility as part of their commercial agreement.

Each US Executive Order and Proclamation imposing tariffs specifies the effective date of the tariffs and the cut-off date for goods in transit. These details must be verified individually within each document. The general principle is that goods already in transit should not be subject to the new tariff rates.

Tariffs are calculated based on the commodity code applied at the time of import, not export. Import and export commodity codes differ, and it is the responsibility of the US importer's customs broker to ensure the correct commodity code is used.

However, it remains important for exporters to classify their goods accurately. To assist with this, the UK Tariff Tool and its General Rules of Interpretation provide guidance on the basic classification principles.

Currently, there is no definitive legal confirmation that these tariffs were unlawfully imposed. If the US Supreme Court reaches that conclusion, its final judgment will determine whether refunds are possible.

If refunds are allowed, the US importer would need to apply for and would receive the refund. In cases where the tariff costs were split or passed on to the exporter, it would be up to the importer and exporter to agree on how any refunded amounts are shared.

The Northern Ireland company would need to get in touch with the importer’s customs broker to discuss formalities. It also depends on how the goods were used in the meantime. 

The de minimis threshold for exports from Northern Ireland on goods valued below USD 800 was removed on 29 August 2025.

Read more about the changes to US import rules for low-value shipments from the UK.

Origin can be understood as the economic nationality of a good. All internationally traded goods must have an origin declared to customs at the point of import. Rules of origin establish how the origin of a good is determined.

There are two types of origin: preferential and non-preferential. Both are defined by their respective rules of origin.

Check your goods meet the rules of origin.

Non-preferential origin applies to goods traded between countries that are not linked by any preferential trade agreement, either in the absence of such an agreement or when the goods are not covered by an existing agreement.

Non-preferential origin does not result in a reduction of tariffs but is used for various other purposes, including quotas, anti-dumping, and countervailing duties. It is also applied for trade statistics and labelling requirements. Non-preferential rules of origin are established individually by each country, based on broad international principles.

Preferential origin relates to trade agreements that grant member countries access to each other’s domestic markets at reduced tariff rates. Preferential rules of origin determine whether a good qualifies for the preferential tariff under such agreements. These rules consist of criteria that goods must meet to be considered as originating within the territory covered by the trade agreement. Goods are assessed against these criteria to establish their origin when exported to a free trade agreement (FTA) partner.

The UK–US and EU–US arrangements are not full Free Trade Agreements and do not create preferential origin rights.

Trade with the US therefore operates on the basis of non-preferential origin, which determines which tariff treatment applies, but does not reduce or eliminate tariffs.

This contrasts with full FTAs such as the UK–EU Trade & Co-operation Agreement, where preferential origin can reduce tariffs to zero where product-specific rules and evidential requirements are met.

For exports to the US, it is also important to note that:

• Chamber-issued Certificates of Origin are not accepted by US Customs as primary evidence of non-preferential origin.
• US Customs instead require substantive evidence of substantial transformation, such as bills of materials, production records, and manufacturing processes, to support origin claims.

For US tariffs, companies should use non-preferential origin. This is based on the principle of substantial transformation, which the US Customs and Border Protection defines as: “Substantial transformation means that the good underwent a fundamental change in form, appearance, nature, or character.”

Read guidance on non-preferential origin and substantial transformation.

For the purpose of US tariffs, companies need to determine whether their product underwent a substantial transformation in Northern Ireland or Great Britain based on the substantial transformation rules.

It is important to note that the substantial transformation must occur within the customs territory of the UK (including Northern Ireland) without interruption to be considered sufficient for origin purposes.

Examples of what constitutes substantial transformation - and what does not - can be found in US case law. To view rulings on non-preferential origin cases, use the search function and type “substantial transformation,” either alone or together with your product or industry.

For the purpose of US tariffs, a certificate obtained from the British Chamber of Commerce (BCC) or any other non-US authority is irrelevant. US customs authorities do not accept or consider a valid indication of origin from any foreign certificates of origin. Such certificates will be disregarded for any determination of origin.

For the purpose of US tariffs and substantial transformation, it does not matter. The only criterion is whether the product underwent substantial transformation in the UK prior to export to the US.

For certain sectoral tariffs, such as the steel and aluminium tariffs, there are provisions that exclude US steel and aluminium content from the value of the final product for specific types of products. This must be checked on an individual product basis.

Unfortunately, this cannot be guaranteed. Customs authorities have the discretion to interpret origin on a case-by-case basis. The only way to obtain legal certainty is to secure a binding origin ruling for your product from US Customs. However, this process may currently be challenging due to a high volume of companies seeking rulings.

The importer is ultimately liable for declaring the correct country of origin and paying the appropriate tariffs. However, the exporter possesses the detailed knowledge of how the products were made and where the substantial transformation occurred. Consequently, the importer will rely on the exporter to confirm the origin. Therefore, in practice, it is the exporter’s responsibility to provide this information and determine the origin.

To claim UK origin, all parts must undergo substantial transformation. For preferential origin, they must also meet the conditions of the relevant trade agreements.

No, the deal announced on 8 May 2025 by Prime Minister Keir Starmer and President Trump has not yet taken effect.

To date, only an announcement of the deal in principle has been made, and no legal text has been published. It is worth noting that the announcements from the two sides contained some differences. There is currently no available information on the progress of negotiations or the timeline.

It is also unclear whether any tariffs will be backdated.

Meanwhile, the UK has been permitted to maintain lower tariffs on steel and aluminium products during the recent tariff increase. While a 50% tariff applies to the rest of the world, the UK continues to apply a 25% tariff. This preferential tariff is scheduled to remain in place until negotiations are finalised.

See the legislation for further detail.

The deal has yet to receive formal agreement.
 

The US court ruling only applies to tariffs applied under the International Emergency Economic Powers Act (IEEPA). This would be the reciprocal tariffs announced on 2 April 2025 as well as the following escalation of these tariffs (retaliatory tariffs). The proceedings also mention “fentanyl” tariffs applied on Canada, China and Mexico.

The legal proceedings are ongoing and the outcome is uncertain.

The duty rate chargeable on imports into Northern Ireland is determined by whether the goods are considered ‘at risk’ or ‘not at risk’ of entering the EU.

If deemed ‘at risk’, EU tariffs apply. 

If they are ‘not at risk’, UK tariffs apply.

If a trader has been authorised under the UK Internal Market Scheme (UKIMS), they can move goods under their authorisation and therefore UK tariffs apply.

However, some imports will be considered automatically ‘at risk’. In those cases, EU tariffs are chargeable at the point of import. The importer may subsequently be able to claim any EU duty paid back via the Duty Reimbursement Scheme.

Goods directly imported into Northern Ireland from outside the EU and Great Britain are automatically ‘at risk’ if the associated EU tariff is 3% or more higher than the UK tariff.

Category 1 goods, i.e., goods subject to trade remedies, are also automatically ‘at risk’ when entering Northern Ireland from either Great Britain or the rest of the world (i.e., outside the EU).

Customs countermeasures are actions taken by a country - or by the EU’s 27 Member States collectively - against an offending country in response to perceived violations of international trade rules or threats to their trade interests. These countermeasures can include additional tariffs, quotas, or other import restrictions.

Although the UK published an 'indicative' list of US products that “may be subject to any future UK tariff response” on 3 April 2025, the subsequent announcement on 8 May 2025 that the UK and US had signed an Economic Prosperity Deal suggests that the likelihood of these measures being enacted has diminished.

A trade deal with the US was announced on 27 July 2025.  However, as at January 2026, the European Parliament has halted work on the implementation and ratification of the EU–US trade agreement in reaction to the US tariff threats linked to Greenland. At this stage there is no immediate legal change to the status of the agreement (which had not yet been fully ratified), but the suspension of legislative progress introduces additional uncertainty around its future implementation. 

If the broader EU–US framework agreement becomes further delayed or derailed, it may extend a period in which the baseline EU–US tariff predictability is not legally operational, even if the current framework is legally agreed.
 

The ‘importer of record’ may be able to claim back any tariffs or countermeasures paid on US imports to Northern Ireland via the Duty Reimbursement Scheme if they can provide evidence that the goods remained within the UK internal market or were subsequently exported to countries outside the EU.

If you wish to claim a waiver on import and are completing the declaration yourself using the Trader Support Service, you should do so by selecting the ‘NIAID’ Additional Information code from the drop-down menu at item level on the Supplementary Declaration (SDI).

If you are using an agent or cargo forwarder to clear the consignment on your behalf, you should notify them in advance that you intend to use your waiver allowance against any ‘at risk’ EU tariffs.

If the duty was paid upon import or was deferred using a Duty Deferment Account, you may be eligible to claim repayment or remission of import duty using the Duty Reimbursement Scheme  by providing evidence that the goods either remained within the UK or were subsequently exported outside the UK and EU.

If you want to claim repayment or remission on the basis that you have sold your goods to a business located in Great Britain or a country outside the EU after 30 June 2023, but your goods are subject to EU trade defence measures, you will need to:

• notify the buyer, and
• provide evidence of this notification when making your claim.

You can check the Northern Ireland Online Tariff where you can search for commodity codes and see the relevant tariffs or countermeasures that apply to specific goods imported into Northern Ireland.
 

If goods moved from a distributor in Great Britain to a trader in Northern Ireland are considered ‘at risk’ of entering the European Union, any applicable EU tariffs, including countermeasures, will apply.