This article explores the emerging role of wooden wax-covered writing boards in Kassite administration, as indicated by their mentions in three letters and one cattle account from Kassite period Nippur. Even though the number of textual references is scarce, the use of wooden wax-covered writing boards is supported by the depictions on late Kassite kudurru monuments. By incorporating perspectives from Middle Assyrian texts and Neo-Assyrian sealings, this study interprets references to writing board usage in Kassite letters, revealing their role in documenting conscripted workers and their rations. This interpretation finds support in evidence from the Ur III period, contemporary Emar, and the Neo-Babylonian period, collectively suggesting that writing boards were regarded as durable and highly reliable sources. The appearance of seal rings in Babylonia in 13th century BC allows for the hypothesis that wooden wax-covered writing boards could have been sealed in a similar fashion as is assumed for Neo-Assyrian writing boards containing lists of ERIN2.MEŠ troops of the king. Notably, the Kassite period letters indicate that writing boards were archived for minimum of 50 years and were checked to verify claims.