Testamentary refers to letters or documents given to the administrator or personal representative of an estate to show that they are legally allowed to handle the financial and business dealings of the estate. Many institutions and businesses require testamentary letters in order to allow the representative access to any information regarding the decedent's account. Testamentary letters are also called letters of administration and are available through the probate court. These letters may be necessary even in the presence of a will showing that the decedent granted the representative the power to proceed with closing the estate. Probate court certifies the testamentary letters and takes responsibility for their authenticity should it come into question.