Definition of 'National Treatment'
A concept of international law that declares if a state provides certain rights and privileges to its own citizens, it also should provide equivalent rights and privileges to foreigners who are currently in the country. This concept of equality can be found in bilateral tax treaties and also in most World Trade Organization agreements.
Investopedia explains 'National Treatment'
For example, if country A provides special tax breaks for its fledgling pharmaceutical industry, all pharmaceutical companies that have operations in country A will be entitled to the tax breaks, regardless of whether the company is domestic or foreign.
In some situations, national treatment may not be such a great thing. For instance, suppose that a state has a law that allows it to expropriate property. Under national treatment, a foreign firm would technically still be subject to the expropriation law. However, depending on the country, other laws may exists that could limit national treatment to only the upside benefits.