Yes, you can take your niece to Canada for a vacation in 2026, but you must be prepared with specific documentation to avoid issues with the Canada Border Services Agency (CBSA). Because you are not the child's legal guardian, you are required to carry a Consent Letter (also known as a Letter of Authorization) signed by both of the child's parents or their legal guardians. This letter should include their full contact information, the dates of the trip, your contact information while in Canada, and a clear statement granting you permission to travel with her and make medical decisions if necessary. In 2026, it is highly recommended to have this letter notarized to ensure its validity. Additionally, your niece must have her own valid passport (or a NEXUS card if applicable). Without these documents, border officials may deny entry to prevent international child abduction, which is a high-priority safety concern for both the United States and Canada.