Protect the Capitol Act of 2021 This bill places additional restrictions on deployments and other activities of the Capitol Police outside of the areas established by law for its jurisdiction. Current law allows the Capitol Police to deploy officers outside of its jurisdiction subject to prior notification and approval requirements. This bill restricts such a deployment to a defined, limited duration of no more than 30 days. Current law also provides exceptions to the prior notification and approval requirements if the purpose of a deployment is to respond to an imminent threat or emergency, provide protective services, or gather intelligence. This bill applies the 30-day limit to excepted deployments and requires that intelligence gathering deployments must be in response to a specific, identified threat to qualify for an exception. Additionally, the Capitol Police shall not establish or maintain a permanent office outside of the District of Columbia.