An alphabeticalbytopic list is provided below containing information and downloadable PDF forms, when available, or links to external resources. A foreign entity is transacting business in Texas if it has an office or an employee in Texas or is otherwise pursuing one of its purposes in Texas.This page provides links to tax treaties between the United States and particular countries. Treaty of February 2, 1848 (Treaty of Guadalupe Hidalgo). The Treaty of February 2, 1848 established the United States-Mexico international boundary. To transact business in Texas, a foreign entity must register with the secretary of state under chapter 9 of the Texas Business Organizations Code (BOC). Apportioned registration, also known as the International Registration Plan (IRP), lets you obtain registration credentials in one jurisdiction. The Treaties in Force publication lists treaties and agreements currently in force for the United States. It is published annually. The facility, a critical commuter and international trade corridor, is one of the oldest and most congested in the region.