The "Fair Day in Court for Kids Act of 2026" establishes a comprehensive framework to ensure legal representation for unaccompanied children in immigration proceedings. It amends the Immigration and Nationality Act to mandate that the Secretary of Health and Human Services (HHS) appoint or provide counsel, at government expense, for these children as expeditiously as possible after a Notice to Appear or placement in HHS custody. This representation must continue through all stages of the proceedings, including appeals and related matters, even if the child turns 18 or is reunified with a guardian. The bill also requires the Department of Homeland Security (DHS) to provide noncitizens or their counsel with a complete copy of their immigration file within seven days of a Notice to Appear, and prohibits removal proceedings from advancing until these documents are received and reviewed. Furthermore, the Act ensures that unaccompanied children have access to counsel inside all federal detention, holding, and border facilities. HHS is directed to develop model guidelines for legal representation, based on established standards, and to establish infrastructure for recruiting and training pro bono counsel. Counsel's duties include representing the child in all immigration-related matters, appearing in person for hearings and interviews, and advocating for the child's legal interests based on their express wishes. If a child cannot express their wishes, counsel must refer them for an independent child advocate. The bill also requires an annual report from HHS on the provision of counsel to unaccompanied children. Significantly, if HHS fails to appoint or provide counsel for an unaccompanied child, the bill allows for motions to reopen their case without typical limitations, and such a motion will automatically stay the child's removal. The Act authorizes necessary appropriations to the Office of Refugee Resettlement to carry out its provisions.