Letters Testamentary are official documents issued by a Texas probate court that authorize the executor named in a valid Will to act on behalf of the estate. Once the Will is admitted to probate and the executor takes the oath of office (and posts bond if required), the court issues Letters Testamentary as proof of the executor’s authority. Banks, title companies, financial institutions, and government agencies typically require certified copies of Letters Testamentary before allowing the executor to collect assets, manage accounts, sell property, or conduct other estate business.