Dual-track Global Mobility: Aligning Tax And Social Security Rules

Cross-border assignments require employers to navigate two independent regulatory frameworks: social security coordination and income taxation. Although often discussed together, totalisation agreements (TAs) and double tax treaties (DTTs) pursue different objectives. Treating them as interchangeable can create compliance risks and unnecessary assignment costs.

Totalisation agreements coordinate social security systems by preventing double contributions and preserving pension rights during temporary assignments, typically through the detached worker mechanism supported by a certificate of coverage (CoC).

Double tax treaties, generally based on the OECD Model Convention on Income and on Capital, determine tax residence, allocate taxing rights between jurisdictions, and provide mechanisms to mitigate double taxation.