The New Reality of Northern Ireland Trade: From Protocol to Windsor Framework
How Brexit Reshaped UK Trade
When the United Kingdom formally exited the European Union, the shift upended how UK businesses traded, especially those moving goods between Great Britain (GB) and Northern Ireland (NI). Overnight, familiar systems disappeared, replaced by complex rules that demanded quick adaptation.
To prevent disruption, the government introduced the Trader Support Service (TSS) on 1 January 2021. This free programme was designed to keep goods flowing smoothly while helping traders understand and meet the new requirements created by the Northern Ireland Protocol.
From the Protocol to the Windsor Framework
The purpose of the Trader Support Service remains simple: to make trade between GB and NI workable. Yet the legal setting around it has continued to evolve. The later Windsor Framework refined the process, cutting back on excessive paperwork through two distinct trade channels:
- Green Lane: for goods staying within the UK Internal Market Scheme (UKIMS), allowing simplified checks.
- Red Lane: for items considered “At Risk” of entering the EU Single Market, subject to fuller customs controls.
The TSS acts as the bridge that helps traders know which route applies to their goods and ensures they meet every compliance requirement without confusion.
Why the Trader Support Service Matters
For many UK businesses, the TSS has become an essential compliance companion. It offers:
- Hands-on guidance through customs procedures.
- Automatic submission of safety and customs declarations on behalf of traders.
- Free education and training resources explaining each new trade rule.
- Reduced interaction with complex HMRC systems, saving time and cost.
In effect, TSS turns complicated border administration into a managed, user-friendly process so companies can focus on operations instead of paperwork.
Recognizing the Service’s Limits
While the Trader Support Service eases administration, it doesn’t remove legal accountability. The trader remains responsible for providing accurate data from product classification and valuation to original details.
Incorrect or incomplete data can lead to:
- Wrong duty or tariff calculations
- Delays or penalties during inspections
- Even full-scale UK tax investigations if discrepancies reach HMRC
That’s why businesses are encouraged to combine the convenience of TSS with professional support from trusted tax advisory services like Lanop Accountants. Expert accountants ensure all declarations are correct before submission, and every compliance step is documented.
Building a Culture of Compliance
To remain fully compliant under the Northern Ireland Protocol, businesses should strengthen their internal systems by:
- Maintaining precise product classification and tariff codes.
- Keeping a complete audit trail of documents and declarations.
- Scheduling regular data-accuracy checks before and after shipments.
When the Trader Support Service is paired with experienced accounting and tax advisors, companies achieve more than logistical efficiency; they gain true business compliance and long-term protection from costly HMRC audits.
Establishing Foundational Compliance: Your EORI Number Strategy
Why an EORI Number Comes First
Every business that trades across UK borders needs an Economic Operators Registration and Identification number, better known as an EORI number.
It’s the digital ID that lets you communicate with HMRC when goods are imported or exported.
For companies that move products between Great Britain (GB) and Northern Ireland (NI), the process involves two codes rather than one.
Most traders must hold both:
- a GB EORI, which applies to movements within mainland Britain, and
- an XI EORI, which covers transactions linked to Northern Ireland.
This dual requirement may sound technical, but it’s what keeps trade data flowing legally between the UK and the EU systems.
The Role of the XI EORI Number
The XI EORI is not optional it’s a mandatory credential created under the Northern Ireland Protocol.
According to HMRC, you need it if you:
- move goods from Great Britain to Northern Ireland,
- export items from Northern Ireland to a non-EU country,
- submit customs declarations within Northern Ireland, or
- apply for any customs-related decision there.
That short “XI” prefix shows regulators that your business is following the special customs rules that apply only to Northern Ireland.
Without it, shipments can’t be processed through the Trader Support Service (TSS) or cleared at the border.
Prefer watching instead?
Here’s a video summary for you
How to Get the XI EORI
Before you can request an XI EORI, you must already hold a GB EORI.
Once that’s active, you can apply for the Northern Ireland version on GOV.UK.
Here’s what HMRC expects during the application:
- Use the dedicated XI EORI form released after September 2021.
- Upload two pieces of evidence showing a Permanent Business Establishment (PBE) in Northern Ireland examples include a lease, utility bill, or business registration.
- If your company operates mainly outside NI, explain clearly why you need the XI number and how it links to your cross-border activity.
While the process isn’t complicated, many businesses prefer to let professionals handle it.
Working with experienced London tax advisors such as Lanop Accountants ensures the paperwork is right the first time and avoids long administrative delays.
Why Both Numbers Matter
Holding both GB and XI EORI numbers isn’t red tape, it’s what proves your compliance under UK and EU customs law.
Northern Ireland sits in a hybrid position: politically part of the UK yet tied to elements of the EU customs system.
Because of that, goods entering NI must satisfy two parallel sets of rules.
Missing or incorrect EORI details can cause serious issues, including:
- blocked access to the Trader Support Service,
- delayed shipments or returned consignments, and
- possible HMRC penalties for technical non-compliance.
In short, securing the right EORI numbers is the first real test of your company’s trade readiness.
Firms that seek guidance from Lanop Accountants gain not only faster registration but also long-term confidence that every shipment meets full business compliance standards.
The following table summarizes the specific EORI number requirements based on the trader’s activity within the new UK trade ecosystem:
EORI Number Requirements for UK Trade Movements
| Movement / Action | EORI Type Required | Primary Rationale |
|---|---|---|
| Moving goods into NI from GB | XI EORI (must have GB first) | Facilitating customs declarations under the Protocol |
| Moving goods from NI to a Non-EU country | XI EORI (must have GB first) | Making an export declaration in NI |
| Moving goods within GB only | GB EORI | Standard UK HMRC compliance |
| Applying for a customs decision in NI | XI EORI | Required for interaction with NI customs systems |
Mitigating Duty Risk: Navigating ‘At Risk’ vs ‘Not At Risk’ Goods
Understanding the Financial Impact of Duty Risk
One of the biggest financial challenges introduced by the Northern Ireland Protocol is determining whether goods shipped from Great Britain (GB) to Northern Ireland (NI) are considered ‘At Risk’ of entering the EU Single Market.
This classification is not just administrative; it directly affects your bottom line. Goods labelled ‘At Risk’ are immediately charged under the EU’s Common External Tariff, often resulting in unexpected duty costs that can erode profit margins and harm the competitiveness of Northern Ireland trade.
To stay cost-effective and avoid unnecessary charges, traders must work to achieve ‘Not at Risk’ status whenever possible.
Securing the ‘Not at Risk’ Advantage
The most effective route for most UK businesses is to register under the UK Internal Market Scheme (UKIMS).
This government scheme was specifically designed to simplify compliance for companies trading within the UK Internal Market.
With UKIMS authorization, a business can:
- Declare goods as ‘Not at Risk’ if they are intended for end use or sale within Northern Ireland or Great Britain.
- Use simplified customs processes through the Trader Support Service (TSS).
- Avoid the additional tariffs that apply to ‘At Risk’ goods.
However, it’s crucial to complete UKIMS registration before goods are moved into Northern Ireland. Once the shipment has crossed without authorization, you lose access to those simplified procedures, making proactive compliance essential.
Alternative Routes to ‘Not at Risk’ Status
While UKIMS is the easiest option, there are two other recognized ways to classify goods as ‘Not at Risk’, though they require more documentation:
- Zero Tariff Products
- If the EU’s Common External Tariff for a specific item is 0%, that product automatically qualifies as ‘Not at Risk’.
- No duty applies, regardless of where the goods eventually go.
- UK-Origin Certification under the Trade and Cooperation Agreement (TCA)
- Goods proven to be of UK origin can move tariff-free under the UK–EU Trade and Cooperation Agreement.
- This benefit applies even if goods later enter the Republic of Ireland or other parts of the EU.
These methods can be valuable, but they often involve detailed paperwork and strict evidence requirements, especially the Rules of Origin criteria, which can be complex for smaller firms.
Strategic Priority for UK Businesses
For most SMEs and mid-sized enterprises, the practical and safest approach is to obtain UKIMS authorization.
Here’s why it stands out compared to the alternatives:
- Simpler documentation: Proof of destination is easier to provide than origin verification.
- Predictable process: Avoids fluctuating tariff classifications.
- Direct alignment with TSS: Works seamlessly with the Trader Support Service for customs declarations.
In contrast, relying on TCA preferences or Zero Tariff listings can introduce risk due to stricter evidence requirements or limited product eligibility.
That’s why experienced professionals such as Putney accountants and tax advisory experts at Lanop Accountants strongly advise clients to secure UKIMS approval early. It remains the most reliable way to protect against unexpected duties while maintaining full business compliance.
The key mechanisms for avoiding unnecessary tariffs are outlined below:
Criteria for Declaring Goods ‘Not at Risk’ (Duty Management)
| Criteria | Definition / Condition | Implication |
|---|---|---|
| Zero Tariff Goods | The EU’s Common External Tariff is 0% for that item | Automatically ‘Not at Risk’; no duty applied |
| UK Internal Market Scheme (UKIMS) | Registered for UKIMS and goods stay in NI or return to GB | Goods declared ‘Not at Risk’ via simplified process |
| TCA Preference | Goods qualify as UK origin under the Trade and Cooperation Agreement | Tariff-free access claimed, even if goods move to the EU |
The Declaration Engine: How the Trader Support Service Works in Practice
Turning Complex Customs Rules into a Practical System
Behind the Trader Support Service (TSS) sits a very deliberate design.
It was built to take the dense paperwork of customs control and turn it into a clear, step-by-step process.
Instead of forcing every trader to master multiple digital platforms, the TSS relies on a structured model called the Simplified Journey, a method developed from the government’s Customs Freight Simplified Procedures (CFSP). This split between logistics speed and administrative accuracy is what allows trade between Great Britain (GB) and Northern Ireland (NI) to function without constant border delays.
What the TSS Actually Handles
In day-to-day use, the Trader Support Service operates as a central digital hub.
It connects traders, hauliers, and customs officials while managing two critical declaration types:
- Customs Declarations: used to calculate import duties and taxes.
These are filed in two parts: the Simplified Frontier Declaration (SFD) when goods leave GB, and the Supplementary Declaration (SD) once they have arrived in NI. - Safety and Security Declarations (SSD): usually submitted as an Entry Summary Declaration (ENS).
This form gives HMRC, and other border agencies advance notice about the cargo for security checks.
The carrier or haulier normally completes this step.
By handling both the fiscal and security sides under one system, the TSS removes a huge amount of manual coordination for traders.
How the Simplified Journey Works
The Simplified Journey is particularly useful for Roll-on/Roll-off (RoRo) ferry routes, where speed is essential.
It breaks the old, rigid customs process into three clean stages:
- Entry Summary Declaration (ENS):
Filed before travel by the haulier; it lists what is being shipped and provides the first layer of safety data. - Simplified Frontier Declaration (SFD):
Generated automatically by the TSS from the ENS information.
This acts as a preliminary customs clearance, letting goods move without waiting for full tax calculations. - Supplementary Declaration (SD):
Completed after arrival by the importer of record.
It includes detailed information about commodity codes, valuation, and origin and finalizes duty and VAT figures.
Because goods can travel using the early declarations alone, ports stay clear, and shipments reach customers faster.
Deferred Compliance and Trader Responsibility
The trade-off for this efficiency is timing.
While the SFD keeps the logistics side moving, the Supplementary Declaration is where the legal and fiscal accuracy must be proven.
That declaration belongs entirely to the importer of record, identified by their EORI number.
If any data in the SD is wrong perhaps a mis-classified tariff or missing origin evidence problems, follow quickly:
- duties may be recalculated,
- additional HMRC charges can appear, and
- compliance reviews or penalties may be triggered.
This is why many businesses choose to have their accounting teams, or trusted advisors such as Lanop Accountants, review every data field before the SD goes in.
One careful audit can prevent weeks of correspondence with customs authorities later.
Navigating the Simplified Journey for GB–NI RoRo Trade
Typical Sequence of Events
For high-volume ferry traffic, understanding the timeline is essential:
- The carrier files the ENS and receives a Goods Movement Reference (GMR).
- The TSS creates the SFD automatically from that data.
- Goods move across the Irish Sea using the issued GMR.
- The importer submits the SD, adding all tax and origin details.
- It must reach HMRC no later than 9 p.m. on the fourth working day of the month following movement.
- TSS compiles a Final Supplementary Declaration each month to confirm that every SD in that period is complete.
Why Expert Oversight Matters
Deadlines are tight, and the amount of data involved is significant.
A single delay or small error in the digital import declaration can lead to penalties or unwanted attention from HMRC.
Working with professionals such as Lanop Accountants helps ensure that:
- tariff codes and valuations are verified,
- every SD aligns with financial records, and
- The company remains fully compliant without interrupting operations.
Their guidance transforms a demanding technical obligation into a smooth, reliable part of your regular workflow.
The table below outlines the responsibilities and timing associated with each stage of the Trader Support Service Simplified Journey:
TSS Simplified Declaration Timeline (GB to NI)
| Declaration Type | Data Required | Timing | Responsible Party |
|---|---|---|---|
| Entry Summary Declaration (ENS) / Safety & Security | Simplified Data Set | Before goods movement | Carrier / Haulier |
| Simplified Frontier Declaration (SFD) | Simplified Data Set (Auto-generated) | Before goods movement | TSS / Trader |
| Goods Movement Reference (GMR) | Movement Reference | Before goods movement | Carrier / Haulier |
| Movement and Clearance | Physical Movement | Actual crossing | Carrier / Haulier |
| Supplementary Declaration (SD) | Full Data Set (Taxes, Tariffs, Origin) | By 9 pm on the 4th working day of the following month | Trader / Importer of Record |
The Critical Window: Accounting, Duty, and the Supplementary Declaration
Why This Stage Defines Financial Compliance
The efficiency of the Trader Support Service (TSS) is often judged by how smoothly goods move across the Irish Sea.
Yet the real measure of success lies beyond logistics.
What truly matters is how accurately a business reports the duty and tax attached to every shipment.
That difference between moving goods and accounting for them is where most compliance risks appear for UK businesses
The Supplementary Declaration: The Point of Fiscal Truth
When the Supplementary Declaration (SD) is submitted, it represents the exact moment of fiscal accountability.
Here, traders finalize all calculations for customs duties, VAT, and excise liabilities.
For certain goods, especially alcohol, tobacco, and other excise products, this step has become even more demanding under post-Brexit rules.
Businesses moving these sensitive goods from Great Britain to Northern Ireland must now apply the excise-duty offset mechanism.
It links every digital declaration directly to accurate financial data, creating a clear trail between digital import declarations and internal accounting records.
This shift leaves no room for estimation or delay: every figure must line up with physical stock movements.
When Small Errors Create Big Problems
A single inaccuracy inside the SD can set off a chain reaction:
- Incorrect duty or VAT totals, affecting returns and cash flow.
- Audit triggers caused by mismatched origin or tariff data.
- Possible penalties or reviews under HMRC’s post-movement checks.
Even something as minor as using the wrong commodity code or forgetting to confirm a product’s ‘Not at Risk’ status can render an entire customs entry financially incorrect.
Because the SD data feeds directly into a company’s tax reporting, every line is open to scrutiny.
Why HMRC Links Customs to Tax Enquiries
Since Brexit, HMRC no longer treats customs data as a separate record set.
It is now a vital part of a trader’s financial profile.
Officers trained in forensic accounting routinely compare customs declarations with VAT and corporate tax submissions.
If discrepancies appear, they can expand a small query into a multi-tax investigation covering:
- VAT returns,
- Corporation Tax filings, and
- Self-Assessment reports.
This interconnection is what makes modern compliance so demanding.
A customs entry isn’t just paperwork; it is evidence that can confirm or contradict your financial statements.
Proactive Safeguards for Businesses
Protecting financial integrity now requires systems that bridge trade operations and accounting.
Every business moving goods through Northern Ireland trade routes should:
- Match customs data with accounting records before submission.
- Review tariff and valuation details regularly to catch errors early.
- Seek professional oversight for all high-value or excise transactions.
Firms like Lanop Accountants specialize in this joined-up approach.
Their advisors help clients build internal checks that ensure every declaration aligns with tax data, reducing the risk of an HMRC investigation and maintaining total business compliance.
Future preparedness: the 2025 regulatory horizon
The rules for Northern Ireland trade keep changing. That means compliance isn’t a one-off; it’s ongoing. Keep one eye on policy updates from HMRC and the other on your systems.
ICS2 is coming act now
By 31 December 2025, ICS2 will require richer, pre-departure cargo data. In plain terms: the early safety forms (ENS) will need more detail. If you use the Trader Support Service (TSS), expect those “quick” fields to demand better, verified information. Accuracy matters more than speed.
What the market shows
Recent data shows Northern Ireland exports to the EU rising (around 7% to Ireland), even as overall UK–Ireland trade softens. That tells you two things: NI remains a key trade gateway, and dual compliance (UK + EU rules) is here to stay.
Practical next steps
- Link your customs and accounting systems so declarations feed straight into ledgers.
- Train staff to check origin, valuation, and tariff fields before submission.
- Use experts when needed to speed up fixes and stop small mistakes becoming big problems.
Advisors like Lanop Business and tax advisors help businesses turn these rules from a burden into an advantage: accurate processes, less friction, and fewer surprises.
Comprehensive Accounting Support: Partnering with Lanop Accountants
The sheer volume of technical detail, the constant regulatory adjustments from the Northern Ireland Protocol to the Windsor Framework, and the imminent digital deadlines necessitate indispensable professional guidance. The specialist knowledge and comprehensive service offered by Lanop Accountants provide vital expertise in this highly technical area.
Lanop Accountants operates as dedicated London tax advisors, ensuring that customs compliance is fully integrated with a wider financial strategy. We guarantee that your customs declarations are accurately translated into your financial reports, proactively safeguarding clients against the inadvertent non-compliance that often triggers an HMRC enquiry. Our expertise covers complex financial areas related to trade, including managing duty offset mechanisms and meticulously ensuring goods qualify under various free trade agreements.
When dealing with HMRC, specific expertise is essential. Whether it involves managing detailed correspondence related to the Northern Ireland Protocol or providing comprehensive defence against a full-scale UK tax investigation, our tax advisory services guarantee expert representation. We meticulously handle the challenging administrative load, from aggregating complex paperwork to managing all communications with HMRC officers. By building a robust, fact-based defensive case, we aim to minimize penalties and interest charges, providing peace of mind during highly stressful periods.
Established in 2009, Lanop Accountants began with its first office in Putney accountants in 2010 and has since grown into an industry-leading, fully digital business and tax advisory firm. We utilize cutting-edge cloud technology, including expert Xero accounting support, to deliver scalable accounting support to UK businesses of all sizes. Our deep technical knowledge of UK trade and customs rules, combined with our commitment to the highest standards of business compliance, ensures our clients remain compliant and strategically competitive in the complex modern trading environment.
FAQs
1. What is the Trader Support Service (TSS)?
The Trader Support Service helps UK businesses move goods between Great Britain and Northern Ireland. It manages customs paperwork and guides traders through post-Brexit rules. Anyone involved in shipping or logistics can sign up for free. The TSS makes compliance easier and keeps goods flowing smoothly without added costs or confusion.
2. Why does ICS2 matter for traders?
ICS2 is a new EU system that gathers detailed cargo data before transport. From December 2025, all GB–NI road and rail shipments must meet its standards. For traders using TSS, this means adding more verified details in the Entry Summary Declaration (ENS) to improve border security and reduce customs delays.
3. How can businesses prepare for ICS2?
Start by checking your customs processes and data accuracy. Link accounting and logistics systems so key shipment details update automatically. Train staff on the new rules, especially the ENS form. Getting early help from Lanop Accountants or other experts ensures your business meets all HMRC and ICS2 requirements without stress.
4. How does TSS make trade easier?
The TSS simplifies complex customs work by handling declarations and safety checks on your behalf. It connects traders, carriers, and HMRC, reducing paperwork and preventing shipping delays. Businesses can focus on operations instead of chasing multiple forms or worrying about compliance errors.
5. What if a customs declaration is wrong?
Errors in customs data can trigger HMRC penalties or duty adjustments. A wrong code or missing document may delay goods and even start a tax review. To avoid problems, double-check all figures before submission and seek help from a professional accountant or customs advisor.
6. Why choose Lanop Accountants?
Lanop Accountants combine tax knowledge with trade expertise. They help businesses align customs data with financial systems, stay compliant with HMRC, and prepare for new rules like ICS2. With their guidance, you can prevent costly mistakes and keep your trade operations running efficiently.
Conclusion: Navigating the Northern Ireland Protocol with Confidence
The Trader Support Service is an invaluable administrative mechanism that offers necessary logistical relief for UK businesses moving goods into Northern Ireland. However, administrative simplification should never be misconstrued as a reduction in compliance liability. The underlying complexity persists, manifested through tight deadlines for the Supplementary Declaration, mandatory EORI number requirements, and future mandates like ICS2.
To fully harness the benefits of the TSS ensuring seamless movement, accurate ‘At Risk’ status management, and fiscally sound digital import declarations requires sophisticated, integrated accounting support and proactive tax advisory services. Errors in customs reporting are financial errors that can swiftly trigger costly UK tax investigations.
Lanop Accountants are expert London tax advisors who specialize in integrating dynamic trade compliance with robust financial strategy, enabling clients to move beyond reaction and into strategic preparedness. By partnering with us, you avoid the high costs of non-compliance and secure a stable future in UK trade.
