Tribal Colleges and Universities Teacher Loan Forgiveness Act - Amends the Higher Education Act of 1965 to provide for the cancellation of a specified percentage of the total amount of any Federal Perkins loan, Federal Family Education loan, or direct student loan for each year of employment (up to five) as a full-time teacher at a tribal college or university if the borrower is not in default on such loan.Prohibits a borrower from receiving, for the same service, both a benefit from this Act and a benefit from the National Community Service Act of 1990.Provides that the amount of any loan forgiven under this Act shall not be treated as gross income for Federal tax purposes.