Fact about the Global Mobility and Expat Taxation – as companies become increasingly international, employees are more likely to work across borders, relocate temporarily or permanently, or perform their roles from several countries. These arrangements can provide businesses with greater flexibility and access to international talent, but they also introduce important tax, payroll and social security considerations.
Employers need to understand where an employee becomes tax resident, which country has the right to tax employment income, where social security contributions should be paid and what reporting obligations apply. The answer can vary significantly depending on the employee’s residence, the location where the work is physically performed, the duration of the assignment and any applicable double tax treaty or international social security rules.
To provide businesses with a practical starting point, we prepared a tax overview for global mobility covering 15 countries in cooperation with the Accace Circle business community: Bulgaria, Cyprus, the Czech Republic, Egypt, Estonia, Greece, Hungary, Italy, Lithuania, Morocco, Poland, Romania, Slovakia, Spain and Turkey.
Tax residency: Why the 183-day rule is only part of the picture
One of the first questions in a cross-border employment arrangement is where the employee is considered tax resident.
A stay of more than 183 days is an important residency criterion in many of the countries covered by the overview. Bulgaria, Egypt, Estonia, Greece, Italy, Lithuania, Morocco and Spain, for example, all use a form of the 183-day test. However, the number of days spent in a country is rarely the only consideration.
Other factors may include a permanent home, habitual residence, family ties, economic interests or the employee’s centre of vital interests. Bulgaria, for example, considers permanent address and centre of vital interests alongside the 183-day test. Spain also looks at the individual’s centre of economic interests and may take the residence of a spouse or children into account.
Cyprus illustrates why employers should not rely on a single rule. In addition to the standard 183-day test, Cyprus also provides a 60-day residency rule where the relevant statutory conditions are fulfilled. Lithuania meanwhile includes an additional test based on spending at least 280 days over two consecutive calendar years, subject to a minimum presence in one of those years.
Where an employee could qualify as resident in two countries, the applicable double tax treaty may become crucial in determining the final tax position.
Personal income tax: From flat rates to progressive systems
Personal income taxation differs considerably across the 15 markets.
Bulgaria applies one of the simplest systems in the comparison, with a standard personal income tax rate of 10%. Romania also applies 10%, while Hungary uses a flat rate of 15% and Estonia applies 22%.
Other countries use progressive tax bands. Cyprus ranges from 0% to 35%, Egypt from 0% to 27.5%, Lithuania from 20% to 32% and Turkey from 15% to 40%. Higher top marginal rates apply in countries such as Italy, where the national rates range from 23% to 43%, Greece, where rates extend from 9% to 44%, and Spain, where the general range reaches 47%. Regional or municipal taxes may apply on top of the national rate in some jurisdictions, including Italy.
For internationally mobile employees, however, the headline rate tells only part of the story. Employers must also consider deductions, exemptions, taxable benefits, payroll withholding rules and whether income needs to be allocated between countries according to the days actually worked in each jurisdiction.
Social security: Determining where contributions belong
Social security is another major consideration for international assignments. The rates, contribution bases and division between employer and employee vary substantially.
In Bulgaria, the aggregate social security rate is 24.7%–25.4%, with 14.12%–14.82% paid by the employer and 10.58% by the employee. Health insurance adds another 8%, shared between employer and employee. For 2026, Bulgaria also applies maximum monthly insurance bases that change during the year.
Elsewhere, the structure can look very different. Egypt applies social security rates of 18.75% for employers and 11% for employees. Turkey applies 23.75% and 15% respectively. Lithuania places a comparatively larger share on the employee, with a standard employee contribution of 19.5% and an employer contribution that generally starts at 1.77%, subject to contract type and risk category. Spain, in contrast, has employer social security contributions above 30% under the general scheme.
These differences can have a significant impact on the total cost of an international assignment.
A1 forms and cross-border social security coverage
For employees moving within the EU or EEA, an A1 certificate can be particularly important. It confirms which country’s social security legislation applies and may allow an employee posted temporarily abroad to remain insured in their home country rather than becoming subject to contributions in both jurisdictions.
In Bulgaria, an A1 form may generally cover an overseas assignment of up to 24 months, with processing typically taking 30 days, or 45 days in certain cases. Spain indicates that an A1 certificate may be obtained in up to five days, while Lithuania generally processes applications within 20 working days once all required information has been submitted.
The exact mechanism is not identical everywhere. Turkey, for example, does not use the EU A1 form in the same way and instead relies on certificates issued under applicable bilateral social security agreements.
For employers, obtaining the correct documentation before or during an assignment can help prevent duplicate social security liabilities and later compliance issues.
Cross-border work also brings filing and reporting obligations
Tax residency and contribution rates are only part of global mobility compliance. Businesses also need to establish who is responsible for payroll withholding, employee registration, monthly reporting and annual tax returns.
A Bulgarian tax resident receiving taxable foreign-source income will generally need to file an annual Bulgarian tax return, while double taxation may be relieved under the relevant treaty or domestic rules. Non-residents working in Bulgaria may be subject to monthly withholding by the employer and, depending on their circumstances, may or may not need to submit an annual return themselves.
Other countries apply different filing deadlines and procedures. Spain generally requires annual personal income tax returns by 30 June, Lithuania by 1 May where filing is required, while Turkey generally uses a 31 March deadline for employees obliged to submit an annual return.
Late registration, reporting or payment can also result in penalties, interest and, in serious cases, criminal liability. This makes advance planning especially important when employees begin working across borders.
Explore the full global mobility comparison
Global mobility arrangements rarely have a one-size-fits-all tax or payroll solution. The employee’s residence, work location, assignment duration, employer structure and applicable international agreements all need to be considered together.
The complete tax overview for global mobility provides detailed country-by-country information on:
• tax residency rules
• personal income tax rates and tax periods
• social security and health insurance
• A1 forms and certificates of coverage
• taxation of residents working abroad
• taxation of foreign residents working locally
• filing and reporting requirements
• penalties for non-compliance
Explore the full publication on the Accace website for a detailed comparison of all 15 participating countries.
From local to global: Your expert guide for cross-border growth
This infographic is brought to you by the Accace Circle business community. Access practical insight from industry experts across 60+ countries within Accace Circle, shared through ongoing webinars, podcasts and publications, to support your international expansion.
Data in this infographic reflects the status as of September 11, 2026 and is for informational purposes only. It does not constitute legal advice.
