What is an international assignment?

An international assignment is a temporary arrangement in which an employer posts an employee to work in another country for a defined period, while the home entity typically retains the employment relationship.

Also called a global assignment, expat assignment, or cross-border posting, international assignments give companies a reliable mechanism for moving talent across borders, whether to fill a skills gap, develop future leaders, or deliver a specific project. The employee works in the host country but remains employed by the home company throughout. Workers in such arrangements are often called an expatriate or expat.

International assignment types: short-term and long-term

International assignments fall into two broad categories based on duration. Short-term assignments generally run for less than 12 months. Long-term assignments typically last one to three years.

Duration shapes every compliance requirement: immigration permit types, tax residency status, and social security obligations all differ based on how long the worker stays in the host country. A posting that begins as short-term can trigger different compliance rules if it extends past the original end date, so tracking actual time in the host country is essential.

For a closer look at each type, see short-term assignment and long-term assignment.

Who remains the legal employer during international assignments?

In a traditional international assignment, the employee stays on the home-country employment contract and payroll. The home entity remains the legal employer, responsible for the employment relationship, compensation, and benefits. The employee works in the host country but is not locally employed there.

Many companies document the arrangement through a secondment agreement, a formal addendum that sets out the terms, duration, and conditions of the posting for both employment law and tax purposes. Where the host country mandates specific local employment terms, those provisions may supplement the home contract for the assignment's duration.

Immigration and work authorization

Most countries require a work permit or work visa before a foreign national can begin working locally. The home employer typically sponsors the application. In the United States, the United States Citizenship and Immigration Services (USCIS) handles intracompany transferee petitions under the L-1 visa category, the standard route for cross-border employee moves. In the United Kingdom, employers need a Sponsor Licence from the Home Office before placing a worker on a Skilled Worker or intracompany transfer visa.

Processing times vary widely, from a few weeks to several months, so immigration planning should begin well before the intended start date. Starting work before the host-country permit is granted exposes both the employee and employer to immigration violations and potential penalties.

Tax and social security

Tax exposure is typically the most complex compliance obligation in an international assignment. An assigned employee may owe income tax in both the home and host country. Most countries have bilateral double taxation treaties that determine which jurisdiction has primary tax rights, but treaty provisions vary significantly by country pair.

To protect employees from carrying a higher tax burden, many companies implement a tax equalization policy. Under tax equalization, the company adjusts the employee's net pay so they pay roughly what they would have paid at home. The company absorbs any excess host-country tax and recoups any shortfall through annual true-up calculations, typically coordinated by home and host tax advisers.

Social security contributions add another layer. Many host countries expect contributions to their own system once a worker is present. Totalization agreements, bilateral treaties that coordinate social security obligations between two countries, may allow an assigned employee to continue contributing to the home country's system for a defined period. This prevents double contributions. Eligible periods and covered countries vary by agreement.

Payroll and compliance risks

Even when the employee remains on the home payroll, the host country may require a shadow payroll for local tax withholding and reporting. Shadow payroll is a local payroll record that mirrors the employee's compensation for reporting purposes without changing where the employee actually receives payment.

Some companies use a split-payroll arrangement instead, paying part of the salary in the home country and part in host-country currency, to meet local cost-of-living or benefit contribution obligations.

A less obvious risk is permanent establishment (PE). If the assigned employee's activities create a fixed place of business in the host country, or if the employee habitually concludes contracts on the company's behalf there, those activities can trigger a taxable corporate PE. Legal review before the assignment starts helps identify and mitigate this exposure.

Do I need an Employer of Record (EOR) for an international assignment

Not necessarily. In an international assignment, the home company stays the employing entity. No local legal entity is required to take on the employment relationship. Therefore, an EOR may not be required to engage the worker in the host country.

EOR is often the right choice for companies making a permanent hire in a country where they have no entity, or where a local employment contract is required from day one. International assignments suit companies moving an existing employee temporarily while preserving the home employment relationship.

How Deel Mobility supports international assignments

Deel Mobility helps companies manage compliance across cross-border assignments, including immigration case management, work permit and visa applications, and coordination of tax and payroll compliance. For more information, see Deel's immigration and visa support.

International assignment key facts

• Assignment types: Short-term assignments generally last under 12 months. Long-term assignments typically run one to three years.

• Legal employer: The home entity usually retains the employment relationship and continues payroll throughout.

• Work authorization: Most host countries require a work permit or work visa before the employee can begin work.

• Tax equalization: Companies commonly equalize tax so employees pay no more than they would at home. Double taxation treaties reduce the underlying exposure.

• Social security: Totalization agreements may permit continued home-country contributions and prevent double contributions.

• Permanent establishment: Assignment activities that create a fixed business presence or authority to bind the employer in the host country can trigger corporate tax liability.

FAQ

What is the difference between a short-term and a long-term assignment?

Duration is the primary distinction: short-term assignments generally run under 12 months and long-term assignments typically last one to three years. Duration also drives different immigration permit types, tax residency rules, and social security obligations.

Does an internationally assigned employee need a work permit?

Yes, in most countries. The home employer typically sponsors the application, and the employee cannot legally begin work in the host country until the relevant authorization is in place.

How does an international assignment differ from EOR employment?

In an international assignment, the home company remains the legal employer. With EOR, a local entity in the host country takes on the employment relationship. EOR suits permanent hires, and assignments suit temporary postings where the home contract stays in force.

What is tax equalization in the context of an international assignment?

Tax equalization is a company policy adjusting an assigned employee's net pay so their tax burden mirrors what they would have paid at home. The company absorbs any excess host-country tax and recoups any shortfall through annual calculations.

Can an international assignment create permanent establishment risk?

Yes. If the employee's activities constitute a fixed place of business in the host country, or include authority to habitually conclude contracts on the company's behalf, those activities may create a taxable corporate presence that triggers local corporate tax obligations.

Tax, immigration, and social security rules vary by country and bilateral treaty, so companies should confirm specific requirements with qualified legal or tax advisers in each relevant jurisdiction.