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Guernsey Tax Identification Number (TIN) Guide

Guernsey, a Crown dependency in the Channel Islands, does not use a single universal tax number. Instead, the Guernsey Revenue Service issues different identifiers depending on whether the taxpayer is an individual, a locally incorporated company, a foreign entity, a partnership, a foundation, a charity, or a trust. This guide covers every identifier type, their formats, and key compliance obligations — including the 2023 independent taxation shift and the 2025 Pillar Two rules that now affect large multinationals operating in Guernsey.

Social Insurance Number​

The Social Insurance Number (SIN) is the primary tax identifier for individuals in Guernsey. It is issued by the Guernsey Revenue Service either at birth (for Guernsey-born residents) or on attaining residency. It serves the equivalent function of a tax identification number for Common Reporting Standard (CRS) and FATCA reporting purposes.

Format: Two-letter prefix GY followed by six digits — for example, GY123456. Numbers are issued sequentially.

Pre-1979 UK and Jersey numbers: Before 1979, individuals relocating permanently to Guernsey from the UK or Jersey were sometimes permitted to retain their original UK or Jersey insurance numbers. This legacy category is small, but financial institutions should recognise a UK National Insurance Number (NINO) or Jersey Social Security Number as a potentially valid TIN for Guernsey-related CRS reporting in such cases.

Independent taxation from 2023: Until 31 December 2022, married couples and civil partners shared a single tax reference number and filed jointly. From 1 January 2023, every individual is assessed separately and holds their own Tax Reference (TRP) number. Approximately 12,000 spouses who had shared a partner's TRP were issued new individual reference numbers ahead of the change.

UK National Insurance Number (NINO)​

A UK NINO follows the format: two letters, six digits, one final letter (A, B, C, or D) — for example, QQ 12 34 56 A. As noted above, pre-1979 holders who moved to Guernsey may still hold a NINO as their effective Guernsey TIN. See the United Kingdom TIN guide for NINO validation details.

Jersey Social Security Number​

A Jersey Social Security Number begins with the two-letter prefix JY, followed by six digits and a final letter — for example, JY 123456 A. This format is closely related to Guernsey's GY-prefixed SIN and may appear in cross-island CRS reporting. For full context, see the Jersey TIN guide.

Company Registration Number​

For businesses incorporated in Guernsey, the TIN is the Company Registration Number issued by the Guernsey Registry. Registration numbers start at 1 and increase sequentially — the number ranges from one to six digits (formats: X through XXXXXX, where X is a digit 0–9).

The official company search portal is at portal.guernseyregistry.com.

Foreign Entities Tax-Resident in Guernsey​

Companies with Guernsey tax residency but not incorporated locally receive a Tax Reference Number issued by the Guernsey Revenue Service. Format: a single digit, followed by a letter, followed by six digits — with an optional letter suffix. Example: 1C 123456 / O.

Partnerships Registered in Guernsey​

The TIN is the Partnership Registration Number issued by the Guernsey Registry, available via the Guernsey Registry website.

Partnerships Registered Outside Guernsey but Tax-Resident Here​

The TIN is the Tax Reference Number (TRN) issued by the Guernsey Revenue Service. Format: a single digit, two letters, six digits, with an optional letter suffix. Example: 1PP 123456 / F.

Foundations​

The TIN is the Foundation Registration Number from the Guernsey Foundations Registrar. Numbers start at 1 and increase sequentially — one to three digits (formats: X, XX, XXX).

Charities​

The TIN is the charity registration number from the Guernsey Charities Register. Format: prefix CH followed by one to three digits — examples: CHX, CHXX, CHXXX.

Non-Profit Organisations (NPO)​

NPO registration numbers use the prefix NP followed by one to three digits — examples: NPX, NPXX, NPXXX.

Trusts​

Guernsey-resident trusts do not receive a TIN or functional equivalent. For CRS/FATCA reporting, the TIN field for a Guernsey trust must be reported as NOTIN.

Guernsey and VAT​

Guernsey is not part of the UK VAT system or the EU VAT area, and there is no general value-added tax (VAT) in Guernsey. Businesses supplying goods or digital services to Guernsey-resident consumers therefore do not face a Guernsey VAT registration requirement — though obligations may still arise in other jurisdictions. See the worldwide VAT registration thresholds guide and the country VAT name directory for a broader comparison.

For Channel Islands neighbours operating under distinct but related tax frameworks, see the Isle of Man TIN guide and the Jersey TIN guide.

Frequently Asked Questions​

My employer is based outside Guernsey — do they have to register for ETI and pay social security contributions?​

Non-Guernsey businesses have no legal obligation to register for the Employees' Tax Instalment (ETI) scheme or to pay the employer share of social security contributions. However, if your overseas employer does not pay the secondary (employer) share, this directly damages your personal contribution record and can reduce your entitlement to the state pension and other benefits. The Revenue Service cannot enforce payment from a non-Guernsey employer. The recommended workaround is for the Guernsey-resident employee to operate payroll themselves and remit contributions under a formal agreement with the overseas company. [1]

Guernsey switched to independent taxation in 2023 — why did my tax reference number change?​

Before 1 January 2023, married couples and civil partners shared a single tax reference number and filed a joint return, with the lead taxpayer (typically the older or male spouse) responsible for the couple's affairs. From 2023, every individual is assessed separately with their own TRP number. Approximately 12,000 spouses who had previously shared a partner's TRP received a new individual reference number ahead of the change. The 2022 return was the last joint return; from the 2023 tax year each person must file individually. Unused allowances can still transfer between spouses automatically when assessments are finalised, but both returns must be submitted first. [2] [3]

What is the penalty for filing a Guernsey income tax return late?​

Penalties are applied automatically if a return is not received by the deadline. The initial penalty is GBP 100, followed by a daily penalty of GBP 10 for every day the return remains outstanding. For taxpayers whose income falls below the personal allowance, the total penalty is capped at GBP 50 once the return is eventually filed. The standard annual filing deadline is 30 November (reinstated from the 2025 year of charge; the 2024 return deadline was extended to 31 January 2026 due to technical issues with the online system). Penalties can be appealed within 30 days of the penalty order on grounds such as a life-threatening illness that genuinely prevented filing. [4]

Does Guernsey's 0% corporate tax rate still apply given the new Pillar Two rules from 2025?​

The standard 0% corporate income tax rate is unchanged for most Guernsey companies. However, two groups face higher rates: companies earning income from Guernsey Financial Services Commission-regulated activities (banking, insurance, fiduciary services, fund administration) pay 10% on that income; large retail businesses with taxable profits above GBP 500,000 from Guernsey land or property pay 20%. From 1 January 2025, Guernsey implemented a Qualified Domestic Top-up Tax (QDMTT) under OECD Pillar Two rules: MNE groups with consolidated annual revenues of EUR 750 million or more must appoint a Domestic Filing Entity, register with the Revenue Service — failure to register can result in penalties of up to GBP 20,000 — and their effective tax rate in Guernsey is brought to 15%. [5]

Does living in an Open Market property in Guernsey count toward Local Market residential qualification?​

No. Time spent in an Open Market property does not accrue toward Local Market residential qualification. Under the Population Management Law, Local Market qualification requires time spent in Local Market accommodation — typically 8 consecutive years for Established Resident status. Open Market residents can live and work in Guernsey indefinitely but remain restricted to Open Market housing unless they already hold a Local Market certificate. The tax cap for new Open Market residents is separate: those who pay GBP 60,000 or more in document duty on a Part A Open Market property qualify for a reduced annual tax cap of GBP 60,000 for four years (versus the standard GBP 160,000 cap on non-Guernsey source income), but paying this cap does not accelerate access to Local Market housing. [6]

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