Anyone who wants to stay in Latvia for more than 90 days in a 180-day period needs a residence permit. That single sentence is where the simplicity ends. Latvian immigration law recognises a long list of legal grounds, each with its own evidence set, its own validity period and its own quirks, and the ground you choose determines almost everything that follows — how long the permit lasts, whether you may work, whether your family can join you, and how the years count towards permanent status later.