This act consolidates and reforms the law relating to immigration and asylum in the United Kingdom. It establishes a new framework for considering asylum claims, introduces measures to combat illegal immigration, and outlines the rights and responsibilities of immigrants and the government.

As a piece of primary legislation, the Immigration and Asylum Act, 1999, is regarded as a foundational document for UK immigration and asylum policy. Its provisions have been subject to extensive legal interpretation and have shaped subsequent policy developments and court decisions. The act's structure and content reflect the legislative priorities and societal concerns of the late 1990s regarding immigration and refugee status.