Global Business Mobility Visa: Tax and National Insurance Implications for Seconded Workers in the UK

When an overseas business sends staff to the UK under the Global Business Mobility (GBM) Secondment Worker visa, the immigration question is only the first hurdle. The moment that worker sets foot in the UK and begins performing duties, a series of UK tax and National Insurance obligations arise for both the worker and the receiving UK entity. These obligations apply from day one, regardless of how short the posting is.

This article sets out what businesses and their advisers need to understand before a GBM secondment begins.

Who Is Affected: The Secondment Worker Route Under GBM

The Secondment Worker visa is designed for professionals seconded to the UK as part of high-value contracts or investments, and permits a stay of up to 12 months at a time, with a maximum of two years in total. Unlike other routes within the Global Business Mobility visa framework such as the Senior or Specialist Worker route, which carries a minimum salary of £45,800 the Secondment Worker route has no immigration salary floor.

Unlike the Senior or Specialist Worker route, the Secondment Worker visa carries no minimum salary threshold. However, the absence of an immigration salary floor does not remove the UK tax and NIC obligations that apply once the worker is here.

UK Income Tax: PAYE From Day One

The Host Employer Rule

Where an employee is working in the UK for someone who is not their direct employer that is, the employee has been seconded the UK host entity will normally be liable to operate both PAYE and NICs under the host employer rules. The statutory basis for this is ITEPA 2003, s. 689. 

In practical terms, this means the UK sponsor company the entity that issued the Certificate of Sponsorship is responsible for operating a PAYE scheme and deducting income tax from the secondee’s earnings attributable to UK duties, even though the worker remains legally employed by the overseas business.

What Earnings Are Taxable?

A GBM secondee is subject to UK income tax on all employment income attributable to UK workdays from the first day of UK working. This includes:

• Basic salary apportioned to UK duties
• Allowances guaranteed for the duration of the UK assignment, such as London weighting
• Benefits in kind provided in connection with UK duties

Where the secondee also performs duties outside the UK, earnings can be apportioned between UK and non-UK workdays, and a Section 690 direction can be sought from HMRC so that PAYE applies only to the UK-duty proportion rather than total earnings.

Short-Term Business Visitor Arrangement

For inbound secondments of under 183 days where the overseas employer has no UK permanent establishment, the Short-Term Business Visitor arrangement HMRC’s Appendix 4 agreement allows a simplified PAYE reporting process, rather than requiring full Real Time Information PAYE from day one. The overseas employer and UK host must both agree to the arrangement with HMRC, and the employee must be resident in a country with which the UK has a double tax treaty. 

This is a useful compliance easement for shorter GBM postings, but it must be formally agreed with HMRC before it can be relied upon.

National Insurance Contributions

Class 1 NIC: Employer and Employee

Once a GBM secondee is working in the UK, Class 1 NIC applies. From 6 April 2025, the rates are:

• Employer (secondary) Class 1 NIC: 15% on earnings above the secondary threshold of £5,000 per year
• Employee (primary) Class 1 NIC: 8% on earnings between £12,570 and £50,270, and 2% on earnings above £50,270

Class 1A NIC, which applies to taxable benefits in kind, is also charged at 15% for the 2025–26 and 2026–27 tax years.

The UK host entity is typically the secondary contributor meaning it is responsible for paying employer NIC and accounting for it through the payroll.

Social Security Certificates and the A1 Position

A GBM secondee arriving from a country that has a bilateral social security agreement with the UK may be able to remain within their home country’s social security system for the duration of the posting, avoiding UK NIC entirely.

Where such an agreement exists, the employer should obtain an A1 certificate (formerly E101) from the home country authority in advance of the secondment commencing. This certifies that the worker remains liable to contribute to the home country social security scheme only, for the period specified, and is therefore exempt from paying NIC in the UK. 

Without this certificate in place before the secondment begins, UK NIC will apply from day one and a retroactive exemption is difficult to achieve.

Double Tax Treaty Interaction

The UK has double taxation agreements with over 100 countries. Under Article 15 of the OECD Model Convention the employment income article used as the template for most UK treaties a secondee may be exempt from UK income tax on their earnings if all three of the following conditions are met:

• The secondee is present in the UK for fewer than 183 days in the relevant 12-month period
• Their remuneration is paid by, or on behalf of, an employer not resident in the UK
• The remuneration is not borne by a permanent establishment of the employer in the UK

It is important to note that income tax treaties apply only to income taxes, not to social security contributions. Even if a secondee is exempt from UK income tax under a treaty, NIC obligations must be assessed separately under the applicable social security agreement.

Permanent Establishment Risk

One of the most frequently overlooked risks in GBM secondments is the potential for the overseas employer to create a UK permanent establishment (PE). A foreign company may become subject to UK corporation tax if it is deemed to have a permanent establishment in the UK, and employing or seconding staff to work in the UK can contribute to establishing that presence.

A PE risk arises where the seconded worker:

• Has authority to conclude contracts on behalf of the overseas employer in the UK
• Habitually exercises that authority from a UK location
• Performs functions that go beyond preparatory or auxiliary activity

If a PE is found to exist, the overseas employer may become liable for UK corporation tax on profits attributable to the UK activities an exposure that sits entirely outside the immigration framework and is often identified only after the secondment has run for some time.

Worked Example

Situation: A technology company headquartered in India seconds a senior engineer to its UK client under a GBM Secondment Worker visa for 18 months, commencing July 2025. The engineer’s annual salary is £60,000, paid entirely by the Indian employer. No A1 or social security certificate has been obtained. The UK client exercises day-to-day management control.

Tax position:

• The UK client is the host employer under ITEPA 2003, s. 689 and must register for PAYE and deduct income tax on UK-workday earnings.
• Class 1 NIC applies from day one. The UK client pays employer NIC at 15% on earnings above £5,000 per year. On a £60,000 salary that is approximately £8,250 in employer NIC per year an additional cost the UK business must budget for.
• Because no A1 certificate was obtained, exemption from UK NIC under any UK–India social security arrangement cannot be claimed retrospectively.
• The engineer is present for more than 183 days, so the double tax treaty 183-day exemption does not apply. UK income tax is due on all UK-workday earnings.
• If the engineer habitually negotiates and concludes contracts with UK clients on behalf of the Indian employer, the Indian employer may have created a UK PE triggering a potential UK corporation tax exposure.

What should have been done:

The business should also have considered whether the 18-month duration and the nature of the role pointed toward a UK Skilled Worker visa as the more appropriate route  particularly given that the Global Business Mobility visa Secondment Worker route has a two-year maximum stay and does not lead to settlement.

Key Obligations Checklist for UK Sponsors

Before a GBM Secondment Worker arrives, the UK sponsor should:

• Register for PAYE with HMRC if not already operating a scheme
• Assess whether a Short-Term Business Visitor arrangement is available for postings under 183 days
• Apply for an A1 or equivalent social security certificate from the home country authority
• Consider a Section 690 direction application where the secondee performs duties both inside and outside the UK
• Review whether the secondee’s activities could create a UK permanent establishment for the overseas employer
• Confirm employer NIC liability and include it in the cost modelling for the secondment

Important: This article provides general information on UK tax and NIC obligations for GBM seconded workers. The correct position depends on the specific facts of each secondment, the applicable double tax treaty, and the social security agreements in force between the UK and the home country. UKPA recommends taking tailored advice before the secondment begins. This article should be reviewed by a qualified chartered accountant or chartered tax adviser before any client-facing use.