Guernsey Tax Reference Number: Format and How to Apply

Tax Identification in Guernsey: What Foreign Owners Need to KnowCopy link to section

A tax ID in Guernsey is not a single universal number. The island works on a system of separate identifiers issued by the Guernsey Revenue Service, with the number you hold depending on whether you are an individual, a locally incorporated company, a foreign entity, a partnership, a foundation, a charity, or a trust.

This affects any foreign owner who incorporates a business on the island, becomes tax resident through a relocating company, or holds Guernsey-source income. The article explains which identifier applies to each entity type, how the numbers are structured, how to register, and where these references are used in filing, banking, and international reporting.

It is most relevant to non-resident business owners and their advisers who need to supply a correct identifier to a bank, a counterparty, or a foreign tax authority and want to be certain they are using the right one.

Does Guernsey Issue a Tax Identification Number?Copy link to section

Strictly speaking, the island does not issue a TIN in the sense used by many other jurisdictions. For Common Reporting Standard purposes, and for individuals only, the Social Insurance number serves as the functional equivalent of a TIN.

Instead of one number for everyone, the Revenue Service assigns different identifiers by taxpayer type. An individual, a local company, a foreign entity, a partnership, a foundation, a charity, and a trust each receive a different kind of reference, or in the case of a trust, none at all.

Guernsey-resident trusts do not get a TIN or any functional equivalent. When a trust appears in a CRS or FATCA filing, the TIN field must be completed as "NOTIN".

One practical limitation matters for advisers: there is no online tool to verify a Guernsey TIN. Validation has to be done against the source document the taxpayer holds.

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The Guernsey Tax Reference Number ExplainedCopy link to section

For individuals, two references run in parallel. Registering with the Revenue Service produces both a Tax Reference Number (TRN) and a Social Insurance Number (SIN), and both may be requested when you contact the authority.

The Social Insurance Number is the primary tax identifier for a natural person. It is issued at birth for those born in the Bailiwick of Guernsey, or on taking up residence, and it carries the TIN function for CRS and FATCA reporting.

A change took effect on 1 January 2023 that advisers should keep in mind. From that date every individual is assessed separately and holds their own Tax Reference number, and roughly 12,000 spouses who had previously shared a partner's reference were issued new individual numbers ahead of the switch.

In a narrow set of pre-1979 cases, UK and Jersey contributors who moved permanently to the island were allowed to keep their existing UK or Jersey Insurance Numbers. A financial institution should treat such a number as a potentially valid Guernsey TIN.

For companies the picture is split by where the firm was formed:

• A company incorporated locally uses its Guernsey registration number, issued by the Guernsey Registry, as its TIN.
• A foreign-incorporated company that becomes tax resident uses the tax reference number issued by the Revenue Service.

Who Must Obtain a Tax ID in GuernseyCopy link to section

Registration with the Revenue Service is required even where you do not believe you owe tax or contributions. Any new organisation, any business that has become tax resident, and any entity with a filing requirement under the economic substance rules must obtain a tax reference number first.

Social Insurance Numbers go to individuals only, never to entities. They are issued at birth within the Bailiwick or when a person moves their residence to the island.

Non-residents with income arising on the island may be liable to income tax there. By law, a non-resident must appoint an agent living in Guernsey, and that agent is responsible for paying the tax and completing the annual return on the non-resident's behalf.

For a foreign-incorporated company, the registration deadline is 14 July following the end of the first calendar year in which the firm is required to file a return.

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Format and Structure of the Guernsey Tax ReferenceCopy link to section

The reference you quote depends entirely on entity type, and the formats do not resemble one another. The table below sets out the structure for each.

The foreign-entity formats are the ones most often confused with a registration number, so a foreign owner supplying a TIN to a bank should confirm which document the number came from before quoting it.

How and Where to Apply Through the Revenue ServiceCopy link to section

The Revenue Service collects income tax and social security contributions across Guernsey, Alderney, and Herm, and it is the issuing authority for tax references. How you obtain a reference depends on where your entity was formed.

For a company, limited partnership, or LLP formed on the island, no separate application is needed. A tax reference is set up automatically using the information passed to the Guernsey Registry on incorporation.

Foreign-formed entities must register actively:

1. A foreign-incorporated company completes a Company Registration Form and submits it to the Revenue Service.
2. A general partnership, or a foreign partnership not formed locally, submits a Partnership Registration Form.
3. A new individual arrival registers to receive a tax reference and social security number before any online services can be used.

Allow 10 to 14 days for a foreign company registration to be processed. Returns and registrations are handled through the MyGov portal; the 2025 corporate return is filed online, with a deadline of 30 November 2026.

The Revenue Service answers its phone lines between 8:45 am and 4:00 pm, Monday to Friday, on 01481 225700, and accepts post at PO Box 37, St Peter Port, GY1 3AZ. A certificate of registration or tax residence can be requested by submitting the relevant form, subject to a £40 administration charge payable before processing.

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Documents Required for RegistrationCopy link to section

Each registrant uses a specific form. A new individual arrival completes the New Arrivals form as soon as possible after moving; a foreign-incorporated company uses the Company Registration Form, which captures the information required under the Income Tax (Guernsey) Law, 1975; a general or foreign partnership uses the Partnership Registration Form.

Several other forms are published on the Revenue Service forms page, including the Company Requesting Non-Resident Status Form, the Request for Company Migration Form, the Company in Liquidation Form, the Company Incorporation Form, the Additional Company Directors Form, and the Form of Authority for Professional Advisers.

A non-resident individual must be registered with the Revenue Service, appoint a locally based agent, report any change in circumstance, and submit the return and pay tax through that agent.

There is no published master list of the supporting identity or corporate documents that must accompany each form, such as certified passport copies or a certificate of incorporation. The current form on the gov.gg forms page is the authoritative source, so an adviser should download the live version and work through its field-by-field requirements before filing.

Distinguishing the Tax ID from Company Registration and Social Insurance NumbersCopy link to section

Because there is no single universal number, confusion between the three common references is the main risk for a foreign owner. Each is issued by a different process and used in a different context.

• Social Insurance Number (the GY number): issued to individuals only by the Revenue Service, and the CRS/FATCA TIN for a natural person; format GY plus six digits.
• Company Registration Number: issued by the Guernsey Registry, not the Revenue Service, to locally incorporated companies; this is the number a bank wants as the TIN for such a company.
• Tax Reference Number: issued by the Revenue Service to foreign-incorporated companies and foreign partnerships that become tax resident; its format differs from the registration number.

For an individual, the SIN and the tax reference number are two distinct identifiers, and both can be needed when dealing with the authority. Both usually appear at the top of a pay slip or on any Revenue Service communication such as a coding notice, statement, or assessment.

One absence is worth stating plainly: there is no VAT number, because the island sits outside the UK VAT system and the EU VAT area and operates no general value-added tax.

Everyday Uses: Filing, Banking, and Self-CertificationCopy link to section

Every company registered on the island files an online tax return each year, and the tax reference is the key that ties that return to the entity. When a bank requests a company's TIN for account opening or review, the figure to supply is the Guernsey tax reference number.

For individuals completing CRS self-certification, the Social Insurance Number stands in as the TIN. Financial institutions reporting under FATCA and CRS for the 2025 period face a deadline of 30 June 2026, as the Revenue Service set out in Bulletin 2026/2, issued on 10 March 2026.

Some individuals need documentary proof of status. A Certificate of Registration or Residence is available from the Revenue Service for the £40 fee, and treaty residence is confirmed through a DTA residence form only where Guernsey holds an agreement with the jurisdiction concerned.

Two routine points round out everyday use. Every communication with the Revenue Service should carry the full name and the tax reference or GY number, and companies paying distributions to Guernsey-resident members must deduct tax and file quarterly distribution returns through the distribution reporter tool on MyGov.

Practical Considerations for Non-Resident Owners and AdvisersCopy link to section

The local agent rule is the single point a non-resident owner cannot work around. The agent living on the island is legally responsible for paying the tax and filing the annual return, and the non-resident must still be registered, keep the authority updated on any change, and route the return and payment through that agent.

The island's reporting reach is wide. It is a party to the OECD's Multilateral Competent Authority Agreement for CRS, in effect from 1 January 2016 with first exchange in 2017, and it signed FATCA Intergovernmental Agreements with the United States on 13 December 2013 and with the United Kingdom on 22 October 2013.

On treaties, the network runs to 17 full double taxation agreements and more than 61 tax information exchange agreements, alongside the OECD Convention on Mutual Administrative Assistance in Tax Matters. For most owners this means a Guernsey identifier may be matched against foreign records under automatic exchange.

Two further developments shape adviser planning:

• Pillar Two: from 1 January 2025 a Domestic Top-up Tax and a Multinational Top-up Tax apply under the OECD GloBE rules, targeting MNE groups with annual revenue of EUR 750 million or more; for the vast majority of entities these rules do not apply.
• Economic substance: companies carrying on activities such as financial services, intellectual property, or distribution must demonstrate substance and report supporting detail in the annual return.

Two operational cautions remain. There is no online tool to validate a Guernsey TIN, so verification rests on the source document, and where a structure has Guernsey-resident individual beneficiaries an adviser should confirm that updated individual Tax Reference numbers were issued after the 1 January 2023 move to separate assessment.

ConclusionCopy link to section

The practical takeaway for a foreign owner is that "tax ID" in Guernsey resolves into a question of entity type rather than a single number. A locally formed company quotes its Registry number, a relocated foreign company quotes its Revenue Service tax reference, and an individual relies on the GY Social Insurance Number, while a trust reports "NOTIN". Knowing which identifier applies, registering on time, and supplying the correct one to a bank or foreign authority avoids the most common errors. Where a non-resident is involved, the mandatory local agent and the registration duty apply regardless of perceived liability.

How Expanship Can Help Your Business in GuernseyCopy link to section

Expanship helps foreign owners obtain and use the correct Guernsey identifier, from registering a relocated company for a tax reference to confirming the right number for bank onboarding and CRS or FATCA self-certification, and the same team supports the wider needs of a foreign-owned entity on the island.

• Company formation and entity setup on the island
• Registered agent and registered office services
• Tax reference registration and annual return filing
• Ongoing compliance and economic substance support
• Accounting and bookkeeping for your entity
• Introductions to banking partners

To discuss your registration or compliance requirements, contact Expanship Guernsey.

Frequently Asked QuestionsCopy link to section